The rotations it has to screw on the quick connect accessory do not correspond to those on the market, so I cannot screw it onto a gun with a quick connect

Although at first I was disappointed and couldn't create a good foam, by trying different proportions, after a few attempts I managed to do it and it is very good. If you use the shampoo with the wax, you will struggle with the foam, it needs a higher ratio than the 1/5 that is recommended, there are also many videos on YouTube about how it works and they are very informative.

I have three foam cannons for use with the convincing Karcher K 7.85 plus (from the old-good Karcher), one from Karcher which is very easy and functional to use (you connect it and start washing, like a bayonet) but with poor results in foam creation, one from Autobrite which after seven or eight uses started leaking at the point where it connects to the pressure washer (I am in contact with the company for warranty), and this...indescribable one from a company that supposedly has a good reputation in the market. First of all, something that I didn't know before purchasing and didn't research, thinking it was obvious that it wouldn't exist, is that the package includes, apart from the adapters for different pressure washers, a tape...Teflon!! Something that I simply HAVE NEVER SEEN ANYWHERE ELSE. I asked the merchant in the store why the tape and he replied...for possible leaks. Great!
Moving on...It has a plastic bottle with a screw (you screw it for ten hours) while it could have been a snap closure with handles (like the Karcher bayonet type), with just one movement. Furthermore, there is no seal between the bottle and the nozzle of the foam cannon, meaning the product comes out of the bottle (in my packaging, there was no elastic gasket to seal the foam cannon ring).
But where it really gave me trouble was when I tried to disconnect the foam cannon, along with the adapter it has for Karcher pressure washers, from the pressure washer gun. The bottle with the foam cannon came out while the adapter remained in the pressure washer gun. THESE DEVICES ARE SUPPOSED TO MAKE YOUR LIFE EASY, NOT DIFFICULT. My whole experience starts with the Karcher foam cannon, which is a model of functionality and ease of use (not performance in foam).
Terrible...wasted money.

Well, the product is worth every penny up to the last cent. You get what you pay for!!!! It was used with Meguiar's Ultimate Snow Foam and a Karcher K4 Full Control pressure washer. The air regulator should be fully open, and the nozzle slightly open!!!! We're talking about real foam, as if you were shaving!!!! In 500ml of water, I added 100ml of soap. With these 600ml, you can wash a car (sportback model) and even clean the wheels with the foam!
First, I was using the Karcher foam sprayer, but it was a disappointment.

I use it with the Karcher K4 Compact 1600psi and Meguiar's Gold Class Shampoo. To create foam, the soap-to-air ratio adjuster must be set to maximum, so I use half of the bottle for each wash, maybe due to the not-so-high pressure of the pressure washer. Also, visually, the foam is not as dense as we see in videos, but rather more diluted. Nevertheless, the result is very good as it quickly spreads the soap everywhere and the soap itself does its job well.