Genuine Canon cam barrel for the EF 50 1.4 USM lenses. 2 types of cam barrels are available. The new style barrel is reinforced at the area most easily damaged when the lens is impacted or dropped. That is the only difference. If you replace a damaged cam barrel with the revised unit, the cam followers YA2-1777 should also be replaced, available here. If you are installing the old style barrel, no upgraded parts are required. We still have plenty of the old style barrels in stock. Made by Canon Japan. Use option to select New or Old style part.