The Mammut Removable Airbag System (R.A.S) ready packs are a backpack that is ready to have the airbag installed. You can use the backpack with or without the airbag system. The Mammut R.A.S is different from the Protection Airbag System (P.A.S); the P.A.S system is a different shaped airbag, similar to a "horseshoe" shape. Whereas the R.A.S is an airbag shaped more like a "pillow". When the R.A.S. is installed the airbag also requires a canister for operation.