These 4 lb. steel sleeves slide easily over the end of the oar, fasten securely to the shaft anywhere you want and are totally removable. This new river tool is fully adjustable and will enable you to offset the weight of the oar outside your oarlocks. You can custom adjust these weights for multiple rowers, personal preferences or for different rowing conditions. These will definitely save some wear and tear on the arms over the course of a long day (or week) on the water. Sleeves are secured to the oar with three 1/4"-20 x 1/2" length nylon pan head screws.