DIY: These high quality 4-pin automotive relays are great for spares or for those looking to build their own relay harness. Don't bother spending two or three times as much for the same thing, or getting less for the same amount of money. Buy Morimoto. PROTECTED:from the elements with 3 layers of silicone seals! Don't trust unsealed relays under the hood that are prone to fail due to moisture. These things are basically impenetrable both rain or shine. INDUSTRY STANDARD: layout includes the switch (85), ground (86), power input (87), and power output (30) INTERNALLY: they are rated to pass 12V at up to 40 Amps through their high quality copper coils. Integrated flyback diode prevents potential back-feeding. STANDARD: Equipment on the HD Relay Harness by Morimoto, you can now build your own harnesses like the pros. OPTIONAL: brackets allow you to combine two relays together on a single mount for a clean setup that designed around more than one relay.