For those that want a totally concealed door sensor, the GE NX458 60-741-95 is the answer. Can be used on most any door and is totally concealed in the door jam. Compatible with all GE alarm systems we sell. Color: White Dimensions: .625" diameter x 3.75" deep hole; magnet requires a .625" diameter, .625" deep hole Batteries: 3.0 VDC custom lithium battery (permanent) Battery life: 15 years