The Resideo 7939WG-BR MPS20 is a surface mount magnetic contact sensor designed for secure installations in doors, windows, and other entry points. Featuring a 1-1/4" gap for effective range and an SPST (Single Pole Single Throw) switch, this contact sensor provides reliable performance. The brown finish ensures it seamlessly blends with wood or darker-colored surfaces, offering both functionality and aesthetic integration into your security system.