diff --git a/contracts/RedeemUtil.sol b/contracts/Bucket.sol
similarity index 51%
rename from contracts/RedeemUtil.sol
rename to contracts/Bucket.sol
index f17eccd..affbf67 100644
--- a/contracts/RedeemUtil.sol
+++ b/contracts/Bucket.sol
@@ -1,7 +1,24 @@
 pragma solidity ^0.6.1;
 pragma experimental ABIEncoderV2;
 
-library RedeemUtil {
+abstract contract Bucket {
+  bool initialized;
+  address payable public owner;
+  address public tokenAddress;
+  uint256 public expirationTime;
+  uint256 public startTime;
+
+  uint256 constant maxTxDelayInBlocks = 10;
+  bytes32 constant REDEEM_TYPEHASH = keccak256("Redeem(uint256 blockNumber,bytes32 blockHash,address receiver,bytes32 code)");
+  bytes32 constant EIP712DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
+  bytes32 DOMAIN_SEPARATOR;
+
+  struct Gift {
+    address recipient;
+    bytes32 code;
+    uint256 data;
+  }
+
   struct Redeem {
     uint256 blockNumber;
     bytes32 blockHash;
@@ -9,7 +26,66 @@ library RedeemUtil {
     bytes32 code;
   }
 
-  bytes32 constant REDEEM_TYPEHASH = keccak256("Redeem(uint256 blockNumber,bytes32 blockHash,address receiver,bytes32 code)");
+  mapping(address => Gift) public gifts;
+
+  modifier onlyOwner() {
+    require(msg.sender == owner, "owner required");
+    _;
+  }
+
+  constructor(bytes memory _eip712DomainName, address _tokenAddress, uint256 _startTime, uint256 _expirationTime) public {
+    initialize(_eip712DomainName, _tokenAddress, _startTime, _expirationTime, msg.sender);
+  }
+
+  function initialize(bytes memory _eip712DomainName, address _tokenAddress, uint256 _startTime, uint256 _expirationTime, address _owner) public {
+    require(initialized == false, "already initialized");
+
+    validateExpiryDate(_expirationTime);
+
+    tokenAddress = _tokenAddress;
+    startTime = _startTime;
+    expirationTime = _expirationTime;
+    owner = payable(_owner);
+
+    DOMAIN_SEPARATOR = keccak256(abi.encode(
+      EIP712DOMAIN_TYPEHASH,
+      keccak256(_eip712DomainName),
+      keccak256("1"),
+      getChainID(),
+      address(this)
+    ));
+
+    initialized = true;
+  }
+
+  function transferRedeemable(uint256 data, Redeem memory redeem) virtual internal;
+
+  function transferRedeemablesToOwner() virtual internal;
+
+  function redeem(Redeem calldata _redeem, bytes calldata _sig) external {
+    validateRedeem(_redeem, maxTxDelayInBlocks, expirationTime, startTime);
+
+    address recipient = recoverSigner(DOMAIN_SEPARATOR, _redeem, _sig);
+
+    Gift storage gift = gifts[recipient];
+    require(gift.recipient == recipient, "not found");
+
+    validateCode(_redeem, gift.code);
+
+    uint256 data = gift.data;
+
+    gift.recipient = address(0);
+    gift.code = 0;
+    gift.data = 0;
+
+    transferRedeemable(data, _redeem);
+  }
+
+  function kill() external onlyOwner {
+    validateExpired(expirationTime);
+    transferRedeemablesToOwner();
+    selfdestruct(owner);
+  }
 
   function getChainID() internal pure returns (uint256) {
     uint256 id;
diff --git a/contracts/GiftBucket.sol b/contracts/GiftBucket.sol
index 102d3ca..aeda192 100644
--- a/contracts/GiftBucket.sol
+++ b/contracts/GiftBucket.sol
@@ -1,67 +1,19 @@
 pragma solidity ^0.6.1;
 pragma experimental ABIEncoderV2;
 
+import "./Bucket.sol";
 import "./erc20/IERC20.sol";
-import "./RedeemUtil.sol";
-
-contract GiftBucket {
-
-  bool initialized;
-
-  address payable public owner;
-
-  IERC20 public tokenContract;
-
-  uint256 public expirationTime;
-  uint256 public startTime;
-
-  uint256 constant maxTxDelayInBlocks = 10;
-
-  struct Gift {
-    address recipient;
-    uint256 amount;
-    bytes32 code;
-  }
-
-  mapping(address => Gift) public gifts;
 
+contract GiftBucket is Bucket {
   uint256 public redeemableSupply;
 
-  bytes32 constant EIP712DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
-  bytes32 DOMAIN_SEPARATOR;
-
-  modifier onlyOwner() {
-    require(msg.sender == owner, "owner required");
-    _;
-  }
-
-  constructor(address _tokenAddress, uint256 _startTime, uint256 _expirationTime) public {
-    initialize(_tokenAddress, _startTime, _expirationTime, msg.sender);
-  }
-
-  function initialize(address _tokenAddress, uint256 _startTime, uint256 _expirationTime, address _owner) public {
-    require(initialized == false, "already initialized");
-
-    RedeemUtil.validateExpiryDate(_expirationTime);
-
-    tokenContract = IERC20(_tokenAddress);
-    startTime = _startTime;
-    expirationTime = _expirationTime;
-    owner = payable(_owner);
-
-    DOMAIN_SEPARATOR = keccak256(abi.encode(
-      EIP712DOMAIN_TYPEHASH,
-      keccak256("KeycardGift"),
-      keccak256("1"),
-      RedeemUtil.getChainID(),
-      address(this)
-    ));
-
-    initialized = true;
-  }
+  constructor(
+    address _tokenAddress,
+    uint256 _startTime,
+    uint256 _expirationTime) Bucket("KeycardGift", _tokenAddress, _startTime, _expirationTime) public {}
 
   function totalSupply() public view returns(uint256) {
-    return tokenContract.balanceOf(address(this));
+    return IERC20(tokenAddress).balanceOf(address(this));
   }
 
   function availableSupply() public view returns(uint256) {
@@ -81,41 +33,21 @@ contract GiftBucket {
     require(gift.recipient == address(0), "recipient already used");
 
     gift.recipient = recipient;
-    gift.amount = amount;
     gift.code = code;
+    gift.data = amount;
 
     require(redeemableSupply + amount > redeemableSupply, "addition overflow");
     redeemableSupply += amount;
   }
 
-  function redeem(RedeemUtil.Redeem calldata _redeem, bytes calldata _sig) external {
-    RedeemUtil.validateRedeem(_redeem, maxTxDelayInBlocks, expirationTime, startTime);
-
-    address recipient = RedeemUtil.recoverSigner(DOMAIN_SEPARATOR, _redeem, _sig);
-
-    Gift storage gift = gifts[recipient];
-    require(gift.recipient == recipient, "not found");
-
-    RedeemUtil.validateCode(_redeem, gift.code);
-
-    uint256 amount = gift.amount;
-    require(redeemableSupply >= amount, "not enough redeemable supply");
-
-    gift.recipient = address(0);
-    gift.amount = 0;
-    gift.code = 0;
-
-    redeemableSupply -= amount;
-
-    tokenContract.transfer(_redeem.receiver, amount);
+  function transferRedeemable(uint256 data, Redeem memory redeem) override internal {
+    require(redeemableSupply >= data, "not enough redeemable supply");
+    redeemableSupply -= data;
+    IERC20(tokenAddress).transfer(redeem.receiver, data);
   }
 
-  function kill() external onlyOwner {
-    RedeemUtil.validateExpired(expirationTime);
-
-    bool success = tokenContract.transfer(owner, this.totalSupply());
+  function transferRedeemablesToOwner() override internal {
+    bool success = IERC20(tokenAddress).transfer(owner, this.totalSupply());
     assert(success);
-
-    selfdestruct(owner);
   }
 }
diff --git a/contracts/GiftBucketFactory.sol b/contracts/GiftBucketFactory.sol
index 8593fb1..77513ee 100644
--- a/contracts/GiftBucketFactory.sol
+++ b/contracts/GiftBucketFactory.sol
@@ -13,7 +13,7 @@ contract GiftBucketFactory {
   }
 
   function create(address _tokenAddress, uint256 _startTime, uint256 _expirationTime) public returns (address) {
-    address p = address(new Proxy(abi.encodeWithSelector(0x9e3d87cd, _tokenAddress, _startTime, _expirationTime, msg.sender), address(GiftBucketImplementation)));
+    address p = address(new Proxy(abi.encodeWithSelector(0x4e9464ed, "KeycardGift", _tokenAddress, _startTime, _expirationTime, msg.sender), address(GiftBucketImplementation)));
     emit BucketCreated(msg.sender, p);
     return p;
   }
diff --git a/contracts/NFTBucket.sol b/contracts/NFTBucket.sol
index 218342e..8c61c1d 100644
--- a/contracts/NFTBucket.sol
+++ b/contracts/NFTBucket.sol
@@ -1,91 +1,26 @@
 pragma solidity ^0.6.1;
 pragma experimental ABIEncoderV2;
 
+import "./Bucket.sol";
 import "./erc721/IERC721.sol";
 import "./erc721/IERC721Receiver.sol";
 import "./erc721/IERC165.sol";
-import "./RedeemUtil.sol";
-
-contract NFTBucket is IERC165, IERC721Receiver {
-  bool initialized;
-
-  address payable public owner;
-
-  IERC721 public tokenContract;
-
-  uint256 public expirationTime;
-  uint256 public startTime;
-
-  uint256 constant maxTxDelayInBlocks = 10;
-
-  struct Gift {
-    address recipient;
-    uint256 tokenID;
-    bytes32 code;
-  }
-
-  mapping(address => Gift) public gifts;
 
+contract NFTBucket is Bucket, IERC165, IERC721Receiver {
   bytes4 private constant _ERC721_RECEIVED = 0x150b7a02; //bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))
 
-  bytes32 constant EIP712DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
-  bytes32 DOMAIN_SEPARATOR;
+  constructor(
+    address _tokenAddress,
+    uint256 _startTime,
+    uint256 _expirationTime) Bucket("KeycardNFTGift", _tokenAddress, _startTime, _expirationTime) public {}
 
-  modifier onlyOwner() {
-    require(msg.sender == owner, "owner required");
-    _;
+  function transferRedeemable(uint256 data, Redeem memory redeem) override internal {
+    IERC721(tokenAddress).safeTransferFrom(address(this), redeem.receiver, data);
   }
 
-  constructor(address _tokenAddress, uint256 _startTime, uint256 _expirationTime) public {
-    initialize(_tokenAddress, _startTime, _expirationTime, msg.sender);
-  }
-
-  function initialize(address _tokenAddress, uint256 _startTime, uint256 _expirationTime, address _owner) public {
-    require(initialized == false, "already initialized");
-
-    RedeemUtil.validateExpiryDate(_expirationTime);
-
-    tokenContract = IERC721(_tokenAddress);
-    startTime = _startTime;
-    expirationTime = _expirationTime;
-    owner = payable(_owner);
-
-    DOMAIN_SEPARATOR = keccak256(abi.encode(
-      EIP712DOMAIN_TYPEHASH,
-      keccak256("KeycardNFTGift"),
-      keccak256("1"),
-      RedeemUtil.getChainID(),
-      address(this)
-    ));
-
-    initialized = true;
-  }
-
-  function redeem(RedeemUtil.Redeem calldata _redeem, bytes calldata _sig) external {
-    RedeemUtil.validateRedeem(_redeem, maxTxDelayInBlocks, expirationTime, startTime);
-
-    address recipient = RedeemUtil.recoverSigner(DOMAIN_SEPARATOR, _redeem, _sig);
-
-    Gift storage gift = gifts[recipient];
-    require(gift.recipient == recipient, "not found");
-
-    RedeemUtil.validateCode(_redeem, gift.code);
-
-    uint256 tokenID = gift.tokenID;
-    gift.recipient = address(0);
-    gift.tokenID = 0;
-    gift.code = 0;
-
-    tokenContract.safeTransferFrom(address(this), _redeem.receiver, tokenID);
-  }
-
-  function kill() external onlyOwner {
-    RedeemUtil.validateExpired(expirationTime);
-
-    tokenContract.setApprovalForAll(owner, true);
-    assert(tokenContract.isApprovedForAll(address(this), owner));
-
-    selfdestruct(owner);
+  function transferRedeemablesToOwner() override internal {
+    IERC721(tokenAddress).setApprovalForAll(owner, true);
+    assert(IERC721(tokenAddress).isApprovedForAll(address(this), owner));
   }
 
   function supportsInterface(bytes4 interfaceID) external override(IERC165) view returns (bool) {
@@ -93,7 +28,7 @@ contract NFTBucket is IERC165, IERC721Receiver {
   }
 
   function onERC721Received(address _operator, address _from, uint256 _tokenID, bytes calldata _data) external override(IERC721Receiver) returns(bytes4) {
-    require(msg.sender == address(tokenContract), "only the NFT contract can call this");
+    require(msg.sender == tokenAddress, "only the NFT contract can call this");
     require((_operator == owner) || (_from == owner), "only the owner can create gifts");
     require(_data.length == 52, "invalid data field");
 
@@ -113,8 +48,8 @@ contract NFTBucket is IERC165, IERC721Receiver {
     require(gift.recipient == address(0), "recipient already used");
 
     gift.recipient = recipient;
-    gift.tokenID = _tokenID;
     gift.code = code;
+    gift.data = _tokenID;
 
     return _ERC721_RECEIVED;
   }
diff --git a/contracts/NFTBucketFactory.sol b/contracts/NFTBucketFactory.sol
index 55add82..7d979f4 100644
--- a/contracts/NFTBucketFactory.sol
+++ b/contracts/NFTBucketFactory.sol
@@ -13,7 +13,7 @@ contract NFTBucketFactory {
   }
 
   function create(address _tokenAddress, uint256 _startTime, uint256 _expirationTime) public returns (address) {
-    address p = address(new Proxy(abi.encodeWithSelector(0x9e3d87cd, _tokenAddress, _startTime, _expirationTime, msg.sender), address(NFTBucketImplementation)));
+    address p = address(new Proxy(abi.encodeWithSelector(0x4e9464ed, "KeycardNFTGift", _tokenAddress, _startTime, _expirationTime, msg.sender), address(NFTBucketImplementation)));
     emit BucketCreated(msg.sender, p);
     return p;
   }
diff --git a/test/contract_spec.js b/test/contract_spec.js
index 64a72cf..8aeb1af 100644
--- a/test/contract_spec.js
+++ b/test/contract_spec.js
@@ -264,7 +264,7 @@ contract("GiftBucket", function () {
     let initialRedeemableSupply = await GiftBucket.methods.redeemableSupply().call();
 
     let gift = await GiftBucket.methods.gifts(recipient).call();
-    const amount = parseInt(gift.amount);
+    const amount = parseInt(gift.data);
 
     const message = {
       blockNumber: blockNumber,
@@ -293,7 +293,6 @@ contract("GiftBucket", function () {
     let expectedRedeemableSupply = initialRedeemableSupply - amount;
     let redeemableSupply = await GiftBucket.methods.redeemableSupply().call();
     assert.equal(parseInt(redeemableSupply), expectedRedeemableSupply, `redeemableSupply after redeem should be ${expectedRedeemableSupply} instead of ${redeemableSupply}`);
-
   }
 
   it("cannot redeem before start date", async function() {
diff --git a/test/nft_contract_spec.js b/test/nft_contract_spec.js
index c4e3e6d..ffd92c9 100644
--- a/test/nft_contract_spec.js
+++ b/test/nft_contract_spec.js
@@ -165,7 +165,7 @@ contract("NFTBucket", function () {
   async function checkGift(recipient, tokenID) {
     let gift = await NFTBucket.methods.gifts(recipient).call();
     assert.equal(gift.recipient, recipient, "gift not found");
-    assert.equal(parseInt(gift.tokenID), tokenID, "token ID does not match");
+    assert.equal(parseInt(gift.data), tokenID, "token ID does not match");
     let tokenOwner = await TestNFT.methods.ownerOf(tokenID).call();
     assert.equal(tokenOwner, NFTBucket._address, "token owner is wrong");
   }
@@ -209,7 +209,7 @@ contract("NFTBucket", function () {
 
   async function testRedeem(receiver, recipient, signer, relayer, redeemCode, blockNumber, blockHash) {
     let gift = await NFTBucket.methods.gifts(recipient).call();
-    const tokenID = gift.tokenID;
+    const tokenID = gift.data;
 
     const message = {
       blockNumber: blockNumber,