The Dichtomatik Tee Seal is a double acting seal that can be used as a direct replacement for an O-Ring. The T-shaped design prevents spiral failure that occurs with O-Rings used in cylinders with long strokes. The Tee Seal uses two Nylon Back-Up Rings as anti-extrusion devices, allowing the Tee Seal to function under much higher pressures than a standard O-Ring.