USA Couplings made according to NFPA 1963 for internal and external binding. Advantage: safe, fast, and easy Bowl Size (Inch) Material Type 1-1/2  X 1-11/16 Aluminum, Brass 1-1/2  X 1-3/4 Aluminum, Brass  1-1/2  X 1-13/16 Aluminum, Brass  1-1/2  X 1-15/16 Aluminum, Brass 2-1/2  X 2-3/4 Aluminum, Brass 2-1/2  X 2-13/16 Aluminum, Brass 2-1/2  X 3 Aluminum, Brass