Keep your oar blades in the vertical position without compromising the feathering ability of open oarlocks. These oar rights fit snugly over the molded oar sleeves with an adjustable inside diameter from 2 - 2 1/4". For Carlisle and Cataract oars, mount the Large Oar-Right on top of the Molded Oar sleeve (as pictured) and don't forget a spare! Large: Fits 2" - 2 1/4" diameter oars (Carlisle & Cataraft Oars with Oar Sleeve) Small: Fits 1 3/8" - 1 5/8" diameter oars (Bluewater Oars and Economy Oars use XS Oar Sleeve)