Sea Dog Plastic Oar Collars. These Adjustable Oar Collars fit standard oars, but can be trimmed for smaller ones. These collars cushion stroke, reduce noise, and prevent wear. Split cover makes it quick and easy to install with brass nails (included). Constructed of rugged, flexible polyethylene. 4-3/16" long, 1-3/4" ID, 7/16" thick collar. Collars can be trimmed to 1-1/2" ID.