The TOTO USA THP4038 O-Ring, with an inner diameter of 37.7 mm and a thickness of 3.5 mm, is designed for reliable sealing in various plumbing applications. Made from high-quality rubber, this O-ring provides excellent resistance to wear and tear, ensuring a leak-free connection. It is compatible with a range of TOTO products, making it an essential component for maintenance and repairs. This O-ring meets industry standards for quality and performance, making it a dependable choice for your plumbing projects.