Nipples are manufactured with a flange from the same family on each end of a tube section. (Fittings that are manufactured with different flange families on each end are called hybrid adapters.) Straight nipples are manufactured with the same size flange on each end of straight section of tubing. Reducer nipples have different size flanges (from the same family) on each end. In addition, reducer nipples are manufactured with straight and conical tube sections. Conical tube sections provide higher conductance. Flexible nipples have tube sections constructed from convoluted (formed metal bellows) tubing. Half nipples are terminated with a tube cuff end on one end for vacuum users with in-house welding capabilities. Nipple fittings are available in all ISO sizes. A&N manufactures standard nipples in 304L stainless steel. Other materials are available on request.