US Seal PS201. This is the industry standard for general pool and spa applications. Buna rubber, Graphitic Plastic seal face. These seals are not recommended for pools or spas with salt chlorine generator, ozonator, or hydrogen peroxide based sanitizer. For these type of applications it is recommended to use the Heavy Duty PS-3868 seal, this seal offers better resistance to abrasion, heat and chemicals. Approximately 13/16" Tall (Not Compressed) 3/4" ID 5/16" Thick White Porcelain Piece: 1 1/4" OD