diff --git a/scripts/build_spec.py b/scripts/build_spec.py
index ca648a754..20e90ee33 100644
--- a/scripts/build_spec.py
+++ b/scripts/build_spec.py
@@ -20,8 +20,8 @@ from eth2spec.utils.ssz.ssz_impl import (
     signing_root,
 )
 from eth2spec.utils.ssz.ssz_typing import (
-    # unused: uint8, uint16, uint32, uint128, uint256,
-    Bit, Container, List, Vector, Bytes, BytesN, uint64
+    Bit, Container, List, Vector, Bytes, uint64,
+    Bytes4, Bytes32, Bytes48, Bytes96,
 )
 from eth2spec.utils.bls import (
     bls_aggregate_pubkeys,
@@ -45,7 +45,7 @@ from eth2spec.utils.ssz.ssz_impl import (
     is_empty,
 )
 from eth2spec.utils.ssz.ssz_typing import (
-    Bit, Container, List, Vector, Bytes, BytesN, uint64,
+    Bit, Container, List, Vector, Bytes, uint64,
     Bytes4, Bytes32, Bytes48, Bytes96,
 )
 from eth2spec.utils.bls import (
diff --git a/test_libs/pyspec/eth2spec/utils/ssz/ssz_impl.py b/test_libs/pyspec/eth2spec/utils/ssz/ssz_impl.py
index 1b59b276b..fd17e29f9 100644
--- a/test_libs/pyspec/eth2spec/utils/ssz/ssz_impl.py
+++ b/test_libs/pyspec/eth2spec/utils/ssz/ssz_impl.py
@@ -1,7 +1,7 @@
 from ..merkle_minimal import merkleize_chunks
 from ..hash_function import hash
 from .ssz_typing import (
-    SSZValue, SSZType, BasicValue, BasicType, Series, ElementsType, Elements, Bit, Container, List, Vector, Bytes, BytesN, uint
+    SSZValue, SSZType, BasicValue, BasicType, Series, Elements, Bit, Container, List, Bytes, BytesN, uint
 )
 
 # SSZ Serialization
diff --git a/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py b/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py
index 5aadfae32..082e3ed30 100644
--- a/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py
+++ b/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py
@@ -123,7 +123,7 @@ class Container(Series, metaclass=SSZType):
                 value = coerce_type_maybe(kwargs[f], t)
                 if not isinstance(value, t):
                     raise ValueError(f"Bad input for class {self.__class__}:"
-                                          f" field: {f} type: {t} value: {value} value type: {type(value)}")
+                                     f" field: {f} type: {t} value: {value} value type: {type(value)}")
                 setattr(self, f, value)
 
     def serialize(self):
@@ -145,7 +145,7 @@ class Container(Series, metaclass=SSZType):
         value = coerce_type_maybe(value, field_typ)
         if not isinstance(value, field_typ):
             raise ValueError(f"Cannot set field of {self.__class__}:"
-                                  f" field: {name} type: {field_typ} value: {value} value type: {type(value)}")
+                             f" field: {name} type: {field_typ} value: {value} value type: {type(value)}")
         super().__setattr__(name, value)
 
     def get_field_values(self) -> Tuple[SSZValue, ...]:
@@ -301,7 +301,7 @@ class Elements(ParamsBase, metaclass=ElementsType):
         v = coerce_type_maybe(v, typ)
         if not isinstance(v, typ):
             raise ValueError(f"Cannot set item in type {self.__class__},"
-                                  f" mismatched element type: {v} of {type(v)}, expected {typ}")
+                             f" mismatched element type: {v} of {type(v)}, expected {typ}")
         self.items[k] = v
 
     def __len__(self):
@@ -400,3 +400,10 @@ class BytesN(BytesLike):
     @classmethod
     def is_fixed_size(cls):
         return True
+
+
+# Helpers for common BytesN types.
+Bytes4 = BytesN[4]
+Bytes32 = BytesN[32]
+Bytes48 = BytesN[48]
+Bytes96 = BytesN[96]
diff --git a/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_impl.py b/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_impl.py
index 8dd04a86d..ae0849098 100644
--- a/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_impl.py
+++ b/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_impl.py
@@ -1,7 +1,7 @@
-from .ssz_impl import serialize, serialize_basic, encode_series, signing_root, hash_tree_root
+from .ssz_impl import serialize, hash_tree_root
 from .ssz_typing import (
-    SSZValue, SSZType, BasicValue, BasicType, Series, ElementsType, Bit, Container, List, Vector, Bytes, BytesN,
-    uint, uint8, uint16, uint32, uint64, uint128, uint256, byte
+    Bit, Container, List, Vector, Bytes, BytesN,
+    uint8, uint16, uint32, uint64, byte
 )
 
 import pytest
diff --git a/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_typing.py b/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_typing.py
index 0f4a06c5f..f604b6468 100644
--- a/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_typing.py
+++ b/test_libs/pyspec/eth2spec/utils/ssz/test_ssz_typing.py
@@ -1,5 +1,6 @@
 from .ssz_typing import (
-    SSZValue, SSZType, BasicValue, BasicType, Series, ElementsType, Elements, Bit, Container, List, Vector, Bytes, BytesN,
+    SSZValue, SSZType, BasicValue, BasicType, Series, ElementsType,
+    Elements, Bit, Container, List, Vector, Bytes, BytesN,
     uint, uint8, uint16, uint32, uint64, uint128, uint256
 )
 
@@ -41,13 +42,13 @@ def test_basic_instances():
 
 def test_basic_value_bounds():
     max = {
-        Bit: 2**1,
-        uint8:   2**(8 * 1),
-        uint16:  2**(8 * 2),
-        uint32:  2**(8 * 4),
-        uint64:  2**(8 * 8),
-        uint128: 2**(8 * 16),
-        uint256: 2**(8 * 32),
+        Bit: 2 ** 1,
+        uint8: 2 ** (8 * 1),
+        uint16: 2 ** (8 * 2),
+        uint32: 2 ** (8 * 4),
+        uint64: 2 ** (8 * 8),
+        uint128: 2 ** (8 * 16),
+        uint256: 2 ** (8 * 32),
     }
     for k, v in max.items():
         # this should work
@@ -161,12 +162,12 @@ def test_list():
     foo[127] = 222
     assert sum(foo) == 999
     try:
-        foo[3] = 2**32  # out of bounds
+        foo[3] = 2 ** 32  # out of bounds
     except ValueError:
         pass
 
     try:
-        foo[3] = uint64(2**32 - 1)  # within bounds, wrong type
+        foo[3] = uint64(2 ** 32 - 1)  # within bounds, wrong type
         assert False
     except ValueError:
         pass