diff --git a/docs/build-decentralized-apps/02-how-to-estimate-gas.mdx b/docs/build-decentralized-apps/02-how-to-estimate-gas.mdx
index 74f660ee9..a9bfd5c1e 100644
--- a/docs/build-decentralized-apps/02-how-to-estimate-gas.mdx
+++ b/docs/build-decentralized-apps/02-how-to-estimate-gas.mdx
@@ -68,6 +68,8 @@ TXFEES = P * (L2G + ((L1P * L1S) / P))
 
 We'll use one resource available in Arbitrum: the [`NodeInterface`](/build-decentralized-apps/nodeinterface/02-reference.mdx).
 
+- B (Extra Buffer) ⇒ The extra buffer is the amount of gas required for posting the transaction on L1, priced in L2 gas.
+  - Call `NodeInterface.GasEstimateComponents()` and get the second element, `baseFee`.
 - P (L2 Gas Price) ⇒ Price to pay for each gas unit. It starts at @@arbOneGasFloorGwei=0.01@@ gwei on Arbitrum One (@@novaGasFloorGwei=0.01@@ gwei on Arbitrum Nova) and can increase depending on the demand for network resources.
   - Call `NodeInterface.GasEstimateComponents()` and get the third element, `baseFee`.
 - L2G (Gas used on L2) ⇒ Gas used to compute the transaction on the child chain. This does not include the _“posting on L1”_ part of the calculations. The value of L2G will depend on the transaction itself, but having the data of the transaction, we can calculate it as follows: