What is "inflator"

Usage examples of "inflator".

The two women shed their packs, and Amerie extracted the fist-sized inflator from hers and studied it.

The impact drove the air out of his lungs, but he automatically hit the inflator on his buoyancy vest and bobbed back to the surface just as the chopper hit, with a tremendous splash, less than thirty meters from his position, one of the still-rotating blades slapping the water not far from his nose and then sinking out of sight as the helicopter rolled over .