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