AN20 is at the top end of the AN range and appears on dry-sump scavenge and pressure lines, large oil cooler circuits and serious fuel systems where flow, not packaging, is the constraint. This straight reusable hose end assembles onto braided hose with the usual socket and nipple arrangement, and the swivelling AN20 nut lets you make the joint without torquing the hose. Large sizes need a firm grip during assembly — use proper aluminium vice jaws and correctly sized spanners rather than adjustables, which will round the flats. Take extra care cutting AN20 hose squarely; a ragged cut makes the socket very hard to start.