Garlock Gylon® 3504 sheet gasketing is made in a process that minimizes cold flow problems associated with skived PTFE gasekt material. Made of virgin PTFE resin and glass microsphere fillers, for high compressibilty. Gylon® 3504 can be used in moderate concentrations of acids and some caustics, hydrocarbons, solvents, water, refrigerants, and cryogenics. Conforms to FDA regulations.