HERCULES QUAD RING 7/32 X 1/16

Four-lobed seals like this one do hold their position better in reciprocating applications. A standard o-ring can roll or twist in the groove during back-and-forth motion, which leads to uneven wear and eventually a leak. The quad ring's profile keeps consistent contact on all four lobes, so it stays stable and doesn't walk around in the groove the way a round cross-section can. For cylinder work especially, that added stability makes a real difference over time.