The Polypipe PP6422M metal pipe stiffener is a robust 22 mm stainless-steel insert designed to support plastic pipes in push-fit plumbing systems. Ideal for use with PolyPlumb, PolyFit or PolyMax fittings, it preserves internal pipe shape, reinforces joints and helps prevent deformation or leaks under pressure or temperature changes. With full compatibility across Polypipe push-fit ranges and reliable long-term performance, this stiffener is suited for professional plumbing and heating installations.