This pure virgin Teflon tape is a full 3.5 - 4 Mil thick and comes in an enclosed plastic spool which has an unlimited shelf life.  Since it is completely synthetic and inert it can be used in a multitude of situations including thread sealing on pipes, sprinkler systems, plumbing lines and automotive work.  Since this tape does not react to the pipe nor does it get hard, the fittings will always come apart easily. This tape is produced under the Dupont trademark.