Click to expand Tap to zoom H K Porter (9134) 'O' Ring - Piston Seal by H K Porter 9190 Pneumatic Cutter & Parts Sale $13.45 | / 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart This 'O' Ring sits in place infront of the piston and acts as a bumper and as a seal H K Porter-9190 Parts Diagram.pdf