Abstract: This disclosure is directed to a protective device for compressed gas cylinders and includes a pair of caps each including an end wall and a peripheral skirt with one of the caps being of a generally inverted frusto-conical configuration and being adapted to receive in a chamber thereof a valve assembly of a compressed gas cylinder, each cap having aligned grooves lying in an axial plane and apertures in the same plane in which and through which, respectively, are disposed strap means for holding the caps positioned upon an associated compressed gas cylinder. The frusto-conical cap includes exterior pairs of projections to prevent rotation of the device about its axis when resting upon a support, as well as internally directed ribs for maintaining alignment between the frusto-conical cap and the compressed gas cylinder.