Rugged, foolproof rack-and-pinion system built into bar which lets you tension chain quickly, correctly, and easily every time. Enhances cutting performance and minimizes wear on the chain. No dead-end spaces to catch and pack sawdust or debris. Helps prevent injury by stopping backward movement of the bar in the event of a mishap. One time removal of tension adjustment pins on standard saws. Fits many small to medium-sized models of the most popular saw brands. Intended for consumer and homeowner use, but are also well suited for commercial work.