This switch button is most commonly used as a bump-button for your starter.

Momentary Push Button Switch (SPST) W/ Boot
Normally Off
5/8"-32 21/32"L (16.7mm) 2 screws
Plastic button and screw-on cap
Rating: 35A at 12V DC, 20A at 24V DC
Contacts: Silver
Housing: Cylindrical diecast body
Circuitry: Off-On, Normally Off. On with button depressed, spring return to Off
Boot Color: Black
Thread: 5/8-32
Dust and weatherproof neoprene rubber