O2 Sidekick Oxygen Roller Bag / Backpack Part#: CD1020 / Mfg: Cramer Decker The all new O2 SIDEKICK is the perfect oxygen cylinder companion for any mobile oxygen user. It's what you've been asking for! This unique bag can be used as a roller bag or a backpack. The bag can accommodate M2, M4, M6, M7, ML6, M9, MD, MJD, or even ME cylinders . Features : · The main front pocket of the O2 SIDEKICK opens using a large EZ-Grab zipper tube puller making it simple to open both front zippers at the same time.