Black anodized microswitch brackets are made from lightweight billet aluminum and fit Holley 4150 and 4500 carburetors for precise activation of the microswitch. Brackets work with the standard secondary arm as well as a throttle adjustment screw secondary arm. Each kit includes a bracket, microswitch and stainless steel hardware securing microswitch to the bracket. ALL54180 includes stainless hardware for mounting bracket to carburetor. ALL54181 mounts to an existing carb stud.