Rubber Oar Stoppers-Pair The 1" thick rubber stopper goes right over the oar shaft, not over the Molded Oar Sleeve. The 1 5/8" inner diameter is a tight fit on the shaft. Use either soap and water or hair spray to lubricate the stopper and shaft to slide it on. As it dries, hair spray also gives an adhesive effect to hold the stopper in place. Sold in Pairs. 1" thick Inner diameter: 1 5/8"