Cebek I-21 is a cyclic timer module with Triac output. The timer is activated by the use a small push button switch. Once the timer has been started it will switch off, after the time¹ you have set it will then switch back on after the time² has timed out. It will keep doing this until the power supply is switched off. The I-21 module has two PCB mounted potentiometers to adjust the on and off times. Not suitable for use with inductive loads.