Durable Material:: The car battery master switch is made of high quality and durable zinc alloy, with copper plating on the surface. The zinc alloy material is high toughness, not easy to be damaged and deformed. This copper plating on the surface can effectively prevent rust and corrosion, with excellent performance of good conductivity. Quick Shutoff:: The automatic top battery switch can allow you to quickly cut off the power of your car battery. It can reduce the power consumption of your car when you are not using it to extend the using time of the car battery. Or when your car is being repaired, you can temporarily cut off the power of your car for safety. Easy to Operate:: First of all, find the negative pole of the car battery, remove the original wiring of the battery pile head. Secondly, place the battery switch on the negative pole of the battery, tighten the screw with a wrench. Third, loosen the knob on the battery switch 4-5 turns to cut off the power of the car battery. Portable Accessory:: This car top rack battery switch measures 2.311.83 inches and weighs 0.24 pounds. Such specification is portable in size and light in weight. It is convenient and easy for you to store it in your car or toolbox and carry it with you everywhere. Special Compatibility:: The battery power cut off isolator is suitable for car batteries with 16-17mm conical terminals. Besides, the rated current is 400A and the maximum withstand voltage is 12V, which makes it suitable for most cars, trucks, vans, SUVs and so on. Product Description Product information: Material: Zinc alloy Quantity: 1pc Color: Black / Red Size: 2.311.83in Weight: 0.24lbs Hole diameter: 17mm Suitable clamp: conical, diameter 16-17mm Product details: – Opening and closing are equally fast and easy. – Removing the black or red handle can prevent theft. – Please install the product in the negative pole position. – It can protect your car by cutting off the power and preventing current leakage. – Loosening this switch can disconnect the car battery, tightening it can turn on the car battery. – The product can better solve the problem that the relay and power consuming devices drain the battery power when you do not start your car for a long time.