When I first installed the brush, the OEM factory screw didn't go all the way in and couldn't secure the brush. I pushed a little harder and it partially ripped off the cheap female end holding the screw. At first I thought this product was a flop until I noticed a tiny packet (less than 3/4 inch) of screws in the corner of the packet, tucked away by all 12 brushes in the bag. I used the included screw and the smaller profile fully engaged the screw. I suggest the seller make it clear that extra screws are included and should be used in place of the larger OEM screws to avoid damaging the hardware. I also noticed that the screw that came with it didn't hold up. It has already fallen off 3 times even though I put it on well so iRobot ran without a brush. OEM screw never did. Last time I put some layers of white tape on it and saw if it held up better.