This model constitutes a bell switch. Bell switch works on the philosophy of shrouded internal mechanism thus preventing visibility of sparks. It also ensures complete protection by incorporating IP 20 protection which guards against accidental contact. The screws used in this are nickel-plated, highly conducive to prevent accidental fire. A bell switch of this category comes in a pack of 20 pieces. The spring in this particular switch is essentially made from EN-42 material.