Meziere Enterprises WCC303 7 Lbs Standard Size Radiator Locking Cap For 3/4" Deep 1-5/8" ID Necks

Meziere's billet aluminum SafeCap has been designed to address several issues that have plagued offroad racers for decades. It easily withstands the rigors of offroad motorsports. Standard caps often get damaged, resulting in the cap coming off at the worst possible time. First you install the cap as normal. Then the half moon shell locks the cap in place and the cotter pin retains the half moon shell. This secures the radiator cap and stops it from turning counterclockwise.

Underneath the cap are a set of brass rollers that spin. On a traditional radiator cap, the stamped steel grinds against your aluminum filler neck and eventually wears the neck out. This cap is expensive, but compare that to welding on a new filler neck or buying a new radiator because your neck is galled from a cheap cap.