Feature:1. Smart Charging: Automatically merge two batteries when charging, and automatically isolate two batteries when not charging.2. Stable Working: Has a voltage sensitive chip to ensure your main battery will provide strong power for vehicle operation.3. Extensive Uses: Allows for wide use on campers, for 4x4, recreational vehicle, marine application and so on, very practical.4. Reliable Using: This dual battery isolator relay can also withstand extreme weather, shock, and it's waterproof as well.5. Easy to Install: There are 4pcs screw and 1pc terminal in the set, bringing more convenience to the installation.Specification:Item Type: Dual Battery RelayProduct Material: ABSColour: BlackContinue Rated Value: DC 125AIntermittent Rated Value: DC 140ABinding Post: M6 (1/4in)Waterproof Grade: IP67Application: Suitable for installation on campers, for 4x4, recreational vehicle and marine application. .Package List:1 x Dual Battery Relay4 x Screw1 x Terminal1 x English User Manual