Towel is lint-free microfiber; color will vary. 

Available either as a 10-pack or 20-pack. Also available with silicone grease instead of towel. 

Disclaimer: FKM and Viton are fluorocarbon. Viton is a name Brand commonly used to refer to FKM and is being used here only in an effort to explain and not as a brand name. There is no implication nor suggestion these are Viton branded. They are O-Ring Depot branded.