The hidden terminal style - 28 series; our standard surface mount with terminals - the 29 series and the vinyl jacketed lead - 29P series are applicable for both residential and commercial installations. All can be installed on a steel surface with a minimum gap penalty. The "P" style is a pre-wired switch with 2 feet of 2 conductor cable. Spacers, terminal covers and mounting hardware are included in package. A broad range of mounting brackets are also available