Rearming kit

An inflatable vest holds a small CO2 cylinder and a trigger, either manual or automatic. Once it inflates, whether from a swim or an accidental soaking, the cylinder is spent and the vest is inert until you fit a new one.

Kits are inexpensive but they are a maintenance obligation. Cylinders corrode, automatic triggers have expiry dates, and an inflatable that has not been checked in three years is a vest you are wearing for reassurance rather than safety.

Foam vests need nothing equivalent, which is a real part of why they suit beginners and anyone who will not keep a maintenance schedule.

Kits are model-specific. Cylinder threads and trigger designs are not interchangeable between manufacturers, so buy the kit for your exact vest and keep a spare with it rather than in a drawer at home.

Automatic triggers fire on contact with water, which includes heavy rain and a wave over the bow. That is one more reason a lot of anglers prefer manual-only inflatables or plain foam.