Engineers have an alternative to traditional sheet-metal joints for making lightweight, compact joints in tubes ranging from 1 to 4 in. in diameter: the Jr. Rigid Coupling from Voss Aerospace, a division of Voss Industries Inc., in Cleveland ( Developed for bleed air ducts on aircraft, the couplings come in a variety of materials, including 347 CRES, A286, Ni 718, 6-4 titanium, and 2024T851. The flanges are made of 347 CRES, Ni 625, 6-4 titanium, and 6061-T6 materials. The coupling and flanges come with all-metal seals and use a safety latch that prevents improper installation.