diff --git a/transaction_fee_models/simulation.py b/transaction_fee_models/simulation.py
index 5f756da..8686e7c 100644
--- a/transaction_fee_models/simulation.py
+++ b/transaction_fee_models/simulation.py
@@ -60,7 +60,7 @@ def run_simulation(params: SimulationParameters) -> Tuple[pd.DataFrame, pd.DataF
         stop_below_gas_limit:bool = _generate_random_bool(params.probability_stop_below_gas_limit)
 
         scale_block_size = np.random.uniform(
-            params.scale_block_size_limits[0], params.scale_block_size_limits[1]
+            0., params.scale_block_size
         )
 
         for chain, pool, tfm, stats in zip(
diff --git a/transaction_fee_models/simulation_parameters.py b/transaction_fee_models/simulation_parameters.py
index 2c33eda..b02a789 100644
--- a/transaction_fee_models/simulation_parameters.py
+++ b/transaction_fee_models/simulation_parameters.py
@@ -11,19 +11,17 @@ class SimulationParameters:
         demand_probabilities: List[float] = [0.05, 0.9, 0.05],
         fee_cap_range:Tuple[float]=(-0.1, 0.1), 
         max_tip_pct:float=0.1,
-        scale_block_size_limits: Tuple[float] = (0.0, 0.2),
+        scale_block_size: float = 0.2,
         probability_stop_below_gas_limit: float = 0.5,
         purge_after: int = 4,
         variable_gas_limits: bool = True
     ):
         assert len(demand_sizes) == len(demand_probabilities), "demand_sizes and demand_probabilities must have the same length"
         assert abs(sum(demand_probabilities) - 1.0) < 1.e-12, "demand_probabilities must sum to 1.0"
-        assert 0.0 <= probability_stop_below_gas_limit <= 1.0, "probability_stop_below_gas_limit must be between 0 and 1"
-        assert len(scale_block_size_limits) == 2, "scale_block_size_limits must be a tuple of length 2"
-        assert scale_block_size_limits[0] <= scale_block_size_limits[1], "scale_block_size_limits must be in increasing order"
         assert all([0.0 <= p <= 1.0 for p in demand_probabilities]), "demand_probabilities must be between 0 and 1"
-        assert scale_block_size_limits[0] >= 0.0, "scale_block_size_limits must be positive"
-        assert scale_block_size_limits[1] <= 1.0, "scale_block_size_limits must be less than or equal to 1.0"
+        assert 0.0 <= probability_stop_below_gas_limit <= 1.0, "probability_stop_below_gas_limit must be between 0 and 1"
+        assert 0 < scale_block_size, "scale_block_size must be strictly positive"
+        assert scale_block_size <= 1.0, "scale_block_size must be less than or equal to 1.0"
         assert len(fee_cap_range) == 2, "fee_cap_range must be a tuple of length 2"
         assert fee_cap_range[0] <= fee_cap_range[1], "fee_cap_range must be in increasing order"
         assert max_tip_pct >= 0.0, "max_tip_pct must be positive"
@@ -34,7 +32,7 @@ class SimulationParameters:
         self.demand_probabilities = demand_probabilities
         self.fee_cap_range = fee_cap_range
         self.max_tip_pct = max_tip_pct
-        self.scale_block_size_limits = scale_block_size_limits
+        self.scale_block_size = scale_block_size
         self.probability_stop_below_gas_limit = probability_stop_below_gas_limit
         self.purge_after = purge_after
         self.variable_gas_limits = variable_gas_limits
\ No newline at end of file