This seal, molded from high grade polyester with 5% glass fiber and 5% PTFE, may retrofit the PS1800 seals, considering all dimensions are comparable. This seal material, with a high degree of 'memory', stretches over the piston and snaps in the groove for immediate assembly. These seals also feature low friction and high abrasion and extrusion resistance which helps to eliminate assembly damage. Piston diameter 'F' dimensions are given for pistons without wear rings.