These rings are of much better quality than the set I bought from Revain about 6 months ago and it didn't last long. Torx and flat head screwdrivers are added bonuses and made replacing the o-ring much easier than the first time. As you can see in the picture (the one with 4 o-rings), the new o-rings are much thicker. There are several videos on UTube showing how to replace the o-ring in the motor side brush. I recommend watching one of the many videos for help.