Works with the sign holder stems, and the sign holders with threaded fittings (sold separately). Fits the following hangrail tubing sizes: 1" round, 1-1/4" round, 1" square, and 1/2" x 1-1/2" rectangular. Works with all of our hangrail tubing. 3/8" threaded fitting on clamps attach to the stems, and the stems attach to the sign holders in order to connect to garment racks or hangrail tubing. Chrome finish.