Most universal oil coolers arrive with M22x1.5 threaded ports, which is convenient for the manufacturer and useless for anyone plumbing in AN hose. This adapter screws into that M22x1.5 port and presents an AN10 connection, so a standard hose end threads straight on. AN10 is the usual choice for engine oil cooler feed and return lines, where bore size directly affects how much heat the cooler can actually shed. Buy two per cooler to convert both ports. Compared with the AN8 version, the AN10 keeps restriction lower on larger-capacity engines and longer hose runs. Also useful on transmission and differential coolers using the same M22 port standard.