This is the Zeagle Spare Air Pouch for Pony/Spare Air Bottle Features: Securely mount your pony/spare air bottle to you BCD Elastic nylon material Eliminate unnecessary dangling bottles Made from an elastic nylon weave, this pouch securely holds your spare air bottle allowing it to be quickly zipped and unzipped from your LTD wing. A nylon webbing strap with a hook & loop closure secures the neck of the bottle. You will need the Zeagle Zip Mount Adapter Kit, in order to zip onto your Zeagle BCD.