AN10 Bulkhead Fitting - 18.9mm Quick-Connect Male This AN10 - SAE 18.9mm adapter is used for crankcase ventilation and offers the maximum flow that an AN10 fitting can handle. Additionally, you can easily click this quick-connect on and off with one hand. -Get AN12 flow in an AN10 connection! With a 23% larger inner diameter and more than 50% better flow than a standard AN10-AN10 adapter, this is the obvious choice for crankcase ventilation and other air-handling applications. An AN10-AN10 bulkhead fitting / tank fitting has a 12.1mm inner diameter This AN10 Bulkhead Fitting - SAE 18.9mm Quick-Connect has a 14.9mm inner diameter Connection 1: AN10 (7/8" -14) Connection 2: SAE 18.9mm ID : 14.9mm Wrench Size : 1" Weight : ~25 grams Add the AN10 nut linked below.