The DiversiTech® C165-0090 3/4 in. OD x 5/8 in. ID Coupling (Socket) with Rolled Tube Stop C x C fitting has a seamless construction and can form a permanent, leak-tight connection that resists corrosion and scaling. It's perfect for water, gas, sanitation, air conditioning, refrigeration, and fire protection systems. Ideal in both residential and commercial applications.