Premium Materials & Good Conductivity: The high-current busbar is reinforced with a flame-retardant ABS bottom and a glass-fiber reinforced nylon bottom, which ensures excellent mechanical strength and durability; stainless steel screws and nuts for better resistance to corrosion and rust in salt water or corrosive environments; the distribution bus box is made of tin-plated pure electrical copper, and the maximum current is a brass strip. 【Ideal for Automotive, Solar, and Marine Applications】: The terminal blocks are suitable for power systems such as RVs, solar panels, cars, trucks, yachts, boats, etc. Whether you need to consolidate, distribute, or protect your electrical installation, the DC distribution rail can gather all the wire bundles and neatly organize the cables in vehicles and boats. 【2 bars of 4 M8 bolts】: You will have durable collection rails with 4 M8 bolts, you have many connection points for the red positive pole and the black negative pole with 5/16" holes,