Replacement left side end cap for Dyson DC15, DC21 and DC23 vacuums. The end cap holds the agitator (brush bar) in place and can be removed to service the agitator. If it becomes damaged or missing a replacement end cap is required. When standing behind the vacuum this part would connect to the left side of the cleaner head. Genuine Dyson part: 909549-01 and 909549-03.