National ByPass Single-Wheel 1/4" Offset Hangers for use on National 771D (Stanley BP60) light duty track systems. Replacement hangers for use on bypassing door weighing up to 60lbs. Angled slots allow easy adjustment. Self-aligning wheel system. Permanently lubricated thermoplastic wheels. 7/8" Diameter Wheel. Screws included. Note: This product is also known as 54-1272, BP60-44, STA-BP60-44, S403-092, STA-N344-879 on other websites.