These sliding shower door pulls are constructed of diecast and black rubber sleeves, and they come in a chrome plated finish. This frameless shower door knob system mounts with a through-bolt design, which bolts into a 3/8 in. diameter hole in the sliding glass, shower door panel. This pull set consists of 2 knobs, the shorter knob and screw should be installed from the inside, and the larger threaded knob should be mounted on the outside. This knob attaches with a #6-32 x 1/2 in. Phillips flat head stainless steel screw, and it is used by a variety of tub enclosure, frameless sliding glass shower door manufacturers.