Shutter mechanism inside the receptacle blocks access to the contacts unless a two-prong plug is inserted, helping ensure hairpins, keys, etc., will be locked out. Manufactured to withstand the demands of commercial and institutional applications. Triple-wipe contacts for maximum conductivity and plug retention. Heavy-gauge, rust-resistant steel mounting strap. Shallow design for maximum wiring room in box. Convenient washer-type break-off plaster ears for best flush alignment. Captive mounting screws for fast installation.