Hidden discreetly within the frame of a door, the only visible part of the EV-DW4917 wireless recessed door/window contact once installed is the access cap (available in white or brown). Access caps are either flanged or non-flanged and allow for either a screw-mount or a press-fit installation. A flat head screwdriver is used to change the cap if needed or access the battery. Primarily designed for installation within a door, the transmitter can also be used within the frames of windows. The EV-DW4917 is built with reliable 433 MHz technology, is powered by a replaceable lithium battery and is compatible with all current DSC wireless receivers.