A fitting that forms an angle of less than 180 degrees (3.141 radians) from the straight flow. The boss connections have external and/or internal machine threads (straight threads other than pipe or hose series), and are designed to facilitate a gasket, preformed packing, washer, or the like, to form a seal at the boss. It may have side or heel inle (s) . It is designed to join two bosses or boss fittings on items such as tanks, housings, valve fittings, and the like. Excludes elbow, tube.