A male-to-male reducer with an AN10 flare at one end and AN8 at the other, both on the standard 37-degree AN cone. A single-size step like this is the gentlest kind of transition, keeping the change in bore modest so flow through the joint stays reasonable. It is a common fitting in fuel and oil systems where a main line runs AN10 but a pump, cooler or filter has AN8 ports. Both ends are male, so pair it with female swivel hose ends or female adaptors on either side. Tighten to a firm seat on the flare rather than overtightening, and never apply thread sealant to an AN flare connection.