The 2.5 inch shrink tube worked just fine on my Carlisle oar shaft that measured 1.75 inch diameter with the old blue plastic sleeve removed. When I slid the shrink tube onto the oar shaft, I left about 4 inches of extra tube hanging over at each end. I used a Wagner heat gun and started shrinking the tube in the middle of the oar shaft and worked all the way to one end, then started in the middle again and worked to the other end. Leaving 4 inches of extra at each end was barely enough to account for the shrinkage that occurred during the heating process. My old black plastic oar stop would not slide over a double layer of the blue shrink tube in the manner Aerocam used. I wish it would have, but I shrunk a 2 inch band of the blue tube above and below the oar stop sleeve and that appears it will work to keep the stop in place. Right now, it looks like I am back in business on the river. Thanks to all who contributed to the topic.