It is a braided packing made of pure PTFE thin yarns fiber, almost complete chemical inertia, dimensional stability, low ... frictio It is a braided packing made of pure PTFE thin yarns fiber, almost complete chemical inertia, dimensional stability, ... pistons valve stems, expansion joints, etc. The packing impregnated with PTFE are also available .Spec: 3.0mm - 50mm Pure PTFE Packing