Heat and chemical resistant Teflon washer for connecting to hair rules, hard type commonly used for hull connections. Hard type, white only. Material: Teflon (PTFE) (for food plumbing) with the same outer diameter from 1S to 1.5S. Because the inner diameter is different, please use a gasket that matches the size of the pipe. If the size is not suitable for you, it may cause contamination or fungus colony.