Allstar Red Plastic Fitting Cap for -6AN and 9/16-18 Thread (Pack of 20) fits sizes -6an and 9/16-18 threads and is made from high-quality aluminum. The cap plug kit is a must for keeping debris out of lines and hoses. It is ideal for keeping internal components of dry sump pumps, fuel pumps, pressure regulators, etc. clean during storage. The cap fits 37 degree flared fittings and straight threaded ports. It is sold one set of 20 pieces..