MSD relay modules are designed to be easily installed in most automotive electrical systems where a high amperage relay is needed. These relay modules are perfect use with high amperage electric fuel pumps and high CFM electric cooling fans. Each relay comes with a 40amp fuse, however lower amp fuses can be installed if required. The relay housing comes with a labeled lid that snaps into place providing a clean installation, and protecting the main power stud and triggers from contamination or accidental contact.