This is an adapter for using 1/4" hex shank drill brushes on the 18V Ryobi scrubbers(P4500 P4510 PCL1701). Brushes not included.
The only attachments offered by Ryobi for their P4500 and P4510 scrubbers are large flat brushes. This adapter opens up your options to use any of the 1/4" hex shank brushes on your scrubber. You can run every shape and size and brand of brushes out there including smaller brushes for cleaning wheels, tires(white lettering), bumpers, grills, etc.
The problem with using your regular drill to run hex shank brushes is moisture ruins electric drills. Drills are not rated for a wet environment. Also, a drill is not meant to run continuously for long periods. The trigger on a drill would have to be held down the entire time you're cleaning. It's not made for that while the trigger on these scrubbers can be set to stay on. Using a regular drill to spin hex shank brushes will age the drill very fast.
These dedicated 18V scrubbers are rated for total submersion in water plus they're designed to run for long periods. The other benefit of this adapter is it saves your regular drill.
The retention of the hex shank is a slip fit so if you carry the tool with it pointed straight down the bit can slip out. A simple magnet placed on the inside of the adapter will prevent the brush from sliding out. Note that while this adapter is precisely centered these 18V scrubbers are not pinpoint precision tools like a drill. If you look at the 3-wing mounting head of your scrubber while it is spinning it's not perfectly centered/has a very slight wobble. That mild oscillation might actually be intentional by Ryobi. Either way the pointed nose on this adapter might make it easier to notice.
After design and manufacturing costs + seller fees + PayPal transaction fees + postal shipping fees this is just barely worth selling online because of all the middle men. Otherwise a direct sale would only cost about $30.