KOYO Co. Ltd. is a specialist manufacturer of brass couplings especially for fine diameter pipes. In 2007 the company made a change from using general brass materials to using cadmium-free brass, making all standard products compatible with European RoHS specifications. The company offers a wide range of products including ring joints, push-expansion couplings, hose couplings, tube couplings, screw-in couplings, manifolds, check couplings, and miniature needle valves.