Protect your oar and tighten the open oarlock system with Molded Oar Sleeves. Injection molded polyethylene. Length 11", inside diameter 1 7/8',  fits Carlisle HD or Cataract oar shafts. We recommend the use of Oar Rights, large Plastic Stoppers, or a rubber doughnut with your Molded Oar Sleeves. Plastic Stoppers come with this system.