Ideal for automotive, solar and marine applications: connection blocks power rail it is suitable for power supply systems such as motorhomes, solar panels, cars, trucks, yachts, boats etc. Whether you need to consolidate, distribute or protect your electrical system, DC distribution rail can assemble all wiring harnesses and store cables properly in vehicles and boats 2 pieces 4 x M10 bolt bus rails: you will have durable collecting rails are 4 x M10 bolts, you have many connection points for the red positive pole and the black negative pole with 3/8 inch holes, modular box design, removable for easy wiring configuration Premium materials and good conductivity: high current rail is reinforced fireproof ABS base, fibreglass reinforced nylon base, which ensures excellent mechanical strength.