The Grayling Left Wing Clamp Only has an adjustable nock receiver which is preset for three-fletch arrows and fits all size nocks. The fletching clamp fits snugly to the shaft allowing for a clean glue line every time. A heavy-duty magnet ensures secure positioning. The Grayling Left Wing Clamp Only is constructed of glass-filled nylon for long-lasting life and is available in stright, right or left-helical.