The Beswick miniature M3 external threaded barb fitting can be ordered in 316 stainless steel, 303 stainless steel, or brass. Five different barb sizes are offered to fit tubing IDs ranging from as large as 1/8" ID (3.2mm) to as small as 3/64" (1.2mm) ID.  A captured O-ring face seal at the threaded end of the fitting provides a leak-tight seal. Buna-N is the standard O-ring material. EPDM, Fluorocarbon, Silicone, and Fluorosilicone are optional. Polyurethane tubing, which provides excellent flexibility and resistance to kinking, is a good choice for barbed style fittings but other tubing materials can also be used.