Material: Aluminum-Magnesium Alloy 535Finish: MillI.D. Size: 1-5/8"Pipe Size: 1-1/4"Set Screw Size: 3/8"-16 Thread X 1/2" LengthHex Key Size: 3/16"Can Be Used With Any Pipe Including Aluminum, Galvanized Steel, Stainless Steel And Black IronMakes A "Criss-Cross" Attachment Where Two Angles Do Not Have To Be 90 Degrees Between Three Or Four PipesGreat For Interior Or Exterior RailingsHigh Corrosion Resistance