Watts TC Test Cock 1/4"" M x 1/4"" F (0006635) The Watts TC Test Cock is for use with backflow preventers, isolation valve for gauges, isolation valves for small equipment lines. Watts TC Test Cock Specifications: • Full port ball valve design • Screwdriver slot to open and close • Available 1/8"" M x 1/4"" F (0006630) or 1/4"" M x 1/4"" F (0006635)"