20mm Standard 'D' Pierce Hole. The L&F Echo is a NFC powered cam lock solution for lockers and cabinets. Operated via the mobile app and completely battery free, Echo uses innovative energy-harvesting technology, drawing a minimal charge from your smartphone to seamlessly lock and unlock your locker with ease. The app is available for both iOS and Android operating systems. This unique lock can be fitted left or right handed using the stop plate supplied and also included is a mechanical override key which will operate the non shuttered 10 disc, anti-tamper barrel in case the need arises. . Battery free - captures energy from a smartphone to drive the motor. Motor powered by NFC Technology (Near Field Communication). Mobile app available for iOS and Android. 66mm diameter x 22mm body depth