Used this with the Karcher K3.98 pressure washer (installed the smaller green nozzles) to clean my concrete driveway and wood deck. Made these jobs at least ten times easier and faster than using just the single nozzle pressure wand that comes with the pressure washer. Water feeding the two nozzles within this cleaner cause the nozzles to spin, creating a nice cleaning action. There are bristles along the circumference of this cleaning head that contain the spray within the head and also help to push debris out of the way. There is a "Power" dial on top of the unit that essentially moves the nozzles toward or away from the surface to be cleaned. I used full power (close) to clean the concrete; about 75% power to clean the wood. In use, the cleaning head is pushed much like a sweeper, but less energy is needed to move the cleaning head than a typical carpet sweeper. Buy this, you'll love it.

As a cleaner, there is a reason there are scrub brushes on the bottom all the way around... if you want something clean you must use them along with the two spray jets. As a cleaner you are better off with either of the two spray wands that come with a power washer, they will clean better and faster than this thing will.
That said this thing has one saving grace, it eliminates any over spray or splash back. This is where it is useful as in a garage, or you don't want any over spray in your area of use.
Other than that it serves no use imo.
I am sending mine back.

I ordered a new Karcher K1800 electric pressure washer AND this T300 surface cleaner at the same time. On the Amazon webpage for the new K1700 thru K2000 models Amazon shows this T300 as an add-on accessory. It isn't. After receiving it found out it is compatible with only certain Karcher units. I called Karcher to be sure. There are no adapters available. Note: At the bottom of this webpage for the T300 it clearly states "except models K1700 Cube, K1700, K1800, K1900, and K2000." The only surface cleaner (so far) that fits these K series units is the Karcher 8.755-848.0.

Long story short - bought the Karcher Gun and Hose assembly for $35. The adapter that comes with it connects to my Blue Clean AR383 machine, no problem. It has a quick connect feature that accommodates the Karcher hose. Fruitless chase for adapters led me to this solution. The T300 Cleaner works well, no miracles. I used it on my brick walkway and it livened it up nicely. Next stop the concrete patio in the yard. Think that will work well as that is only dirty. The front brick walkway has some mildew/whatever that would appear to need some kind of chemical cleaning in addition to the water.

I was skeptical of the video that made it look so easy and fast to clean a walkway. But, I have to admit that it is faster than just using the Karcher wands. Looks like it uses more water but it made faster work of the same area. My concrete pad was heavily laden with moss growth. I had to repeatedly pull the surface cleaner back and forth to remove the majority of the moss. I then had to switch to the wand to sweep the loosened debris away and spot clean the stubborn areas. Bottom line for my use: this did a good job and greatly reduced the work time. Normally the long pad would take 5 or 6 hours with just the wand. This cut the time in half. I only encountered one problem, a stone got wedged and prevented the revolving wand from moving. Freak occurrence but if you hear a rattling inside the cleaner tilt a side up to let it discharge the object. Finally, it seemed more gentle on the concrete surface than the harsher blast from the wands.