Electronic "sensor" number lock. Touching the correct numbers a relay will operate. In case that false numbers are touched, the lock will block automatically for some time. The number can be preset freely. Operating voltage: 12 V/DC. Usage : For opening doors and gateways without keys, to switch machines and electronic devices, which should not be operated by unauthorized persons (through latching relay). For DIY electric locks at safes and partition for valuables etc.