A male-to-male reducer with an AN16 flare at one end and AN12 at the other, both to the standard 37-degree AN form. This is the gentle version of the AN16 transition, dropping only one size, which keeps restriction low on the sort of high-volume plumbing that uses AN16 in the first place: scavenge lines, large cooler circuits and substantial fuel returns. Use it where a big line has to meet an AN12 pump, cooler or tank fitting. Both ends being male, it pairs with female swivel hose ends or female couplers. Seat the flares properly and leave sealant off; on an AN joint the cone does the sealing, not the thread.