The Pack Rack Plus is designed for use on ATVs, bicycles, and shooting carts. The aircraft grade aluminum blocks attach to handlebars and any tubular or square bars or railings 1/2 Inch to 1â?쳌 in diameter. The internal steel cores are covered in thick soft rubber. Rubber straps attach over the holder for added security. The rubber fins cushion and grip items. Full 360 degree rotation allows firm grip of different sized objects by simply twisting the holder and locking the wing nut.