Brass 1/2" Barb Coupling. Brass Pipe and Fittings are manufactured for both commercial-industrial and residential standards. Brass has a high level of tolerance, making it ideal for oil, water, and air line applications. Brass fittings are universal, they can be used by professionals and DIY guys. This Brass 1/2" Barb Coupling features 1/2" male threads, and a 1/2" barb connection that's designed to connect tubing.