This is a set of replacement dual action brushes (compatible) for iRobot Roomba 800 and 900 series. ● Replacement Frequency: Recommended replacement is every 6 months to 1 year. *This may vary depending on usage and environment. ● Compatible Models: iRobot Roomba (800/900 series) 870, 871, 875, 876, 878, 880, 885, 890, 891, 892, 893 960, 961, 980, 985, etc. ● Quantity: 2 brushes (Black x 1, Gray x 1) ● Size: Length: 18.5 cm Diameter: 2.5 cm *Slight variations may occur ● Replacement Instructions: ① Push the levers on the frame inward and lift. ② Remove the old aero brush. ③ Install the new aero brush, matching the color and shape of the illustration on the main unit. ④ Close the frame to complete. ● Shipping: Ships same day. ● Packaging: Will be placed in a plastic bag and sent in an envelope. ● Other: As this is a compatible product, the construction may be slightly less refined compared to the genuine product. Please be aware of the above before purchasing.