This product can be severed as main switch, automotive start relay and battery isolator. Put this relay between batteries as an isolator or in the main power. Features: Red copper binding post: ensuring heavy current can be transited safely. High current automotive relay and battery isolator. 12V 500A heavy current relay: great for construction and machinery system. High quality: ensuring the maximum electric current can be transferred. Easy and effortless to use: simple installation. Specifications: Contact load: 500A Contact form: 1A Rated power: 12V Max switching voltage: 14V Mechanical life: 10,000,000 Load material: AgSnO Max switching current: 500A Pin number: 4 pin Contact type: SPST Temperature:-30to+80 Humidity: 40-85 Item size: 8.5 * 5.5 * 7.7cm / 3.3 * 2.1 * 3in (L * W * H) Item weight: 239g / 8.4oz Package size: 9 * 8 * 6cm / 3.5 * 3.1 * 2.3in (L * W * H) Package weight: 252g / 8.8oz Package List: 1 * 4 pin high current relay and battery isolator