It has a little gassey kayak Jack , "O"ooops , sorry about that , Kayak Jack told me about them ( to use ) for the trip we took. Yep..I do listen to what he tells me at times , not all of them , just sometimes.
It has a small compressed gas canaster that inflates it with normal gasses. If it fails then you can manually inflate it.
It is like wearning suspenders , light weight , does not make you a ball of sweat in the summer and is something really nice , even though I hate wearing one.
Play it safe , wear a PFD when on the water , the life it saves is yours.

Chuck.