... save energy.** Stainless steel seat** Unique sealing ring, with saw-tooth sides, embedded directly into disc, bolt-free ... Type butterfly valve features:Features: ** Structural design complies with BS 5155.** End connection acc. BS 4504, Section3.2, ANSI B16 ... tight for long serviceGood exchangeability** Excellent sealing effect** complies with BS 6755, part1, 1986. Valve sizeDN50-DN600Pressure rating ...