OPERATION: This car battery isolator switch is used for DC 12V 24 V systems, On/Off 2 position, Max withstanding current: 12V 200A. Recommended to mount on NEGATIVE battery post.PROTECTIVE CAP: Master battery cut off switch comes with protective waterproof cap, which can better protect the dust and water coming in the key hole.NO MORE BATTERY DRAIN: The battery cut off isolator switches help isolate and secure the electrical system, eliminate any power draw from the battery when vehicle or boat is not in use, disconnects the battery safely.2 * PORTABLE KEYS: The key can be taken down when there is no power connection.PACKAGE INCLUDE: 1 x Battery Disconnect Switch, 2 x Keys, 1 x Waterproof Cover. Size: 2 brass Terminals: 5/16".