3 sprockets (à 6.93 EUR) ordered one is slightly bent, with another abrasions are visible on the plastic, but should not limit the function. In addition, the rings are not 100% determined on the lenses (Canon EF 28, 50 and 85), so I am afraid that this. With prolonged use, certainly could slip from time to time OK for the price, but would draw the next time probably deeper into their pockets and buy something better.
UPDATE: the seller has sent me 2 free new sprockets. There is a star more (formerly 3 stars). Could the sprockets test even now and are okay. Although they seem a bit loose at first glance, but is slipping when turning nothing.