40-663A | SPDT Double Sided Key Switch. Sometimes called a shunt lock. Complete with 2 keys and mounting hardware. Hook up using screw terminals. Used with most alarm equipment and with all Calrad Alarm Modules.125V AC, 4Amp. 250V AC, 2A. Mounts in 1.8" deep hole. Bushing length to connectors 1.8"?, Mounts in .75" hole.