Straight Couplings. A.Y. McDonald Service Fittings are made in the United States of America and are manufactured to meet or exceed the AWWA C800 (latest revision) standard. Our service fittings are rated to withstand the same pressures as the tubing they are designed to fit. They are designed and tested for cold potable water only. EPDM rubber gaskets are used in our compression fittings. The 74755 series fittings are designed to cover any A.Y. McDonald flare end to a different size or end connection.