The Voltcraft DHHM 230 operating hours timer is designed to DIN dimensions with an added countdown timer feature for installation in power supplies, lab equipment and control panels. It fits into a standard module with DIN dimensions 48 by 24mm and and the 6 display digits are 10mm high. The unit can be configured with an alarm set to trigger an optional LED or buzzer upon reaching a pre-set value. Alternatively it can be set-up as a count down timer and the alarm will trigger when the time reaches zero. Instructions are included with the device to connect four optional keys to aid its programming and operation. * Counter range: 99999.9 hrs * Height x width 45 x 22mm * Temperature range from -10 °C to +50 °C. * Requires a 3VDC supply @ 50µA