Good quality n79s replacement wheel, to replace the old, broken, loose, worn or missing casters Easy to replace robot vacuum cleaner wheels, without tools Help your vacuum cleaner change direction, improving its working efficiency. Compatible models: for N79S N79 DN620 DN622 robot vacuum cleaner. Material: plastic + metal color: black Package Contents: 4 x Casters Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in a little different from the real thing. The measurement allowed error is +/- 1-3 cm.