Over time the piston seal in every HPLC system becomes worn and must be replaced. Our piston seals are constructed of PTFE material with an additive that reduces their tendency to "cold flow" and improves their wear characteristics. PTFE seals are more resistant to any HPLC solvent than UHMWPE seals, but they are less wear-resistant and rugged. For Agilent 1050 and 1100 HPLC systems.