Auto Lifejacket, Self Inflating Life Jacket, On Entering Water This Lifejacket Will Inflate Automatically. Before Use Ensure 33gr CO2 Gas Cylinder Is Fitted To 150N Adult Lifejacket Or One 60gr CO2 Gas Cylinder Is Fitted To 275N Adult Lifejackets Or One 22gr CO2 Gas Cylinder To Children's Lifejacket. If The Automatic Inflation For Any Reason Does Not Operate, Use The Back-Up Manual Inflator By Pulling The Manual Lever. One Canister Included With Sale. Medium / Large Size.