THIS SCREW-ON OIL CAP KIT FITS ON AL-KO AND HAYES 7K & 8K AXLES NEWER THAN 1987.THIS KIT INCLUDES: 1. 021-217-00 OIL CAP 1. 010-045-00 O-RING 1. 085-017-00 RUBBER PLUG. CAP THREAD DIAMETER: 2-3/4".