Our CRL Sex Bolt Mounting Screws are perfect for securely attaching any CRL Surface Mounted Door Closer to wood or hollow metal doors. Each pack includes four screws designed for use with 1-3/4" (44.5 mm) thick doors. Specifically intended for mounting closers on hollow core doors, these screws are suitable for use with 1-3/4" (45 mm) doors. Each pack contains four screws.