The North Face Activation Unit
Here's what other sites are saying:
Keep your Patrol 24 ABS Pack or Powder Guide ABS Vest ready to use and always have a spare Activation Unit on hand. This activation unit consists of a canister of compressed nitrogen which is used to inflate the bags because it resists icing at low temperatures and a trigger that activates the canister. Steel cartridge canister should be handled with care and used according to instructions.
- The North Face