Responsive Respiratory - Cylinder Backpack is offered in 2 sizes for M6/M9 and D cylinders. Includes pair (2) of padded adjustable shoulder straps and chest stabilizer strap. The roomy interior with zipper pocket allows you to carry valuables with ease. The padded mesh back wicks away moisture. This backpack is vented for conserver use and has dual grommets. Quick carry handle at top of bag. Color: Black. Sizes: D Cylinder (RRI1501101): 23" H x 10" W x 3 1/2" D. M6/M9 Cylinder (RRI1501151): 15 1/2" H x 10" W x 3 1/2" D.