Material: The shell is made of high-quality plastic, copper terminals with iron hex nuts for better continuity, high temperature resistant, no risk of falling off, durable. Function: Used to isolate the battery and secure the electrical system, eliminating any power consumption from the battery when the vehicle or boat is not in use, safely disconnecting the battery. Additional protection: The battery main switch comes with 2 keys and a weather cover, and the keys also cover the opening when in use, which can better protect dust and water from entering the keyhole. Size: The screw diameter is 8 mm/0.31 inches and the installation opening is 5 mm/0.20 inches. The battery switch is used for DC 12V, rated current: 300A (12V). Wide applications: It can be used as an opening key to open various electrical devices such as radar, chassis, and fog lights, which can be used indoors and outdoors.