ALEKO 10BS-MC18S Magnetic Contact Reed Switch Security Alarm Contact for Doors Windows and Gates Lot of 10 Easy to install without complicated instructions: just drill and insert! Slim terminal connection design is ideal for both residential and commercial applications ABS plastic housing is durable and long lasting Perfect to install on an interior or exterior door, window, gate, or anywhere else that could use some extra protection Package includes (10) sensor sets; Product dimensions: 11 x 17.5 millimeters; Color: White