ZERO VOLTAGE DROP: Forget the traditional diode relays and so-called "solid state" devices that can you of almost 2 amps of output power! The Dual Battery Isolator is the only unit designed with programming to deliver performance - with ZERO sacrifice. This compact battery isolator was built ultra-small (2.6inch x 2.6inch x 2inch) to fit almost anywhere! A perfect fit under the hood to get close to your dual batteries. VOLTAGE SENSITIVE RELAY: The Automatic 140 Amp Dual Battery Isolator is all you need to charge Two Battery Systems. Voltage Sensitive Relay cuts in at 13.3 volts and cuts out at 12.8 volts to your primary battery is always and ready to start your vehicle. It's like having two separate power sources for each battery while only having one alternator! RUGGED DURABILITY: Unlike other isolators on the market, the Automatic 140 Amp Dual Battery Isolator is IP65 Certified. This Protection rating means that your isolator is safe for use even for your off-road needs in dusty,