Our engineers designed the line of Hi-Tek differential covers to not only look good but address a number of weaknesses of the factory stamped steel covers. First, they started by constructing the covers of thick A356.0-T6 aluminum, which dissipates heat much faster than the factory steel unit keeping the fluid temperature lower under high-stress loads vs. a steel cover. Then for added durability, we added a reinforced center bar for extra strength along with load bolts to help prevent bearing cap deflection under severe loads. The internal shape of the cover retains the smooth round back internally to help keep the fluid flow going over the ring gear to properly lubricate the gears and bearings. Additional features include a magnetic drain plug for catching ferrous metal particles, machined B&M logo and all necessary hardware and easy to follow detailed instructions for a quick and simple installation you can do at home. Note: Gasket not included