Replacement Seat Stop for Old Town kayaks outfitted with side bars. The screw can also be used for seats without the ring (remove screw from ring - discard ring). Fits a bar slightly under one inch in diameter. Screw can be turned by hand or with a screw driver. Outside diameter of ring is 1.25 inches. Inside diameter of ring is 15/16 of an inch. Ring is approximately 1.25 inches long. OLDOUT OUTKNOB