The Polypac® PHD Seal is a heavy-duty, compact, double-acting piston seal combining a PTFE slipper ring energized by an NBR elastomer ring and reinforced with two POM backup rings. It delivers outstanding leak control, extrusion resistance, and wear protection over a wide pressure range. The elastomer energizer ensures a tight seal at low pressures, while the PTFE ring engages fully under higher pressure; backup rings guard against extrusion , providing low friction, smooth startup, and a long service life in harsh hydraulic environments