This is the GE Interlogix DesignLine Recessed Door Contact. The TX1510-01- is the industy's most flexible supervised, recessed door contact allowing a multitude of applications while hiding the transmitter within a door frame. The contact uses a replaceable lithium battery and should last five years under normal usage.
The Contact comes with a standard flush mount top and a flanged top. unscrew the top to access the battery or change to a different top.