Pipe thread tape made of Teflon*, white virgin Teflon, .4 density,.003" thick. Over 50% elongation and chemically inert. Provides a strong tight seal for any threaded joint and permits easy disassembly. Tolerates -400 degree F to +500 degree F. For use on oxygen systems, and potable water systems, non-toxic and non-flammable. (Blue spool)