NOTE: This cannula does not include a flowmeter. To purchase the A5 flowmeter, search for "A5 Solopack" SKU:2000047 A5 Boom Cannula is designed to provide easy access to oxygen without sacrificing comfort and performance. With a simple mount to your headset, the A5 Boom Cannula features a swivel arm and fully adjustable cannula to give you the best fit. This cannula version is a single lumen cannula and is compatible with the A5 Flowmeter or any other constant flow oxygen system. The A5 Boom Cannula is convenient, comfortable, lightweight, and works with your existing headset. The A5 Boom Cannula is configured for a left side mount to the headset. NOTE: Oxygen equipment is non-returnable.