This is a 4 pin push switch. By giving VCC to only one pin, you can get output in two pins by pressing the switch once. Commonly these are used as reset switches in projects.are the small version of these switches.We use these little buttons on everything! These Miniature Single Pole Single Throw switches have a good click to them and are breadboard friendly. Perfect as a tactile reset switch. These momentary buttons are rated up to 50mA.