Works very well, I love it!

Comes with no doc.
But the product info and picts on amazon is helpful.
Seems to work fine.
The case needs to be assembled and the paper tape
peeled from the plastic case parts (unless you like cardboard box motif).

Some quality control issues: one of the screws won't fit, had some extra junk (solder?)
on the threads on one unit ( I bought two). And there was some extraneous solder
on one of the mounting holes that I scraped away to make it fit for the 2nd unit.

Arrived as promised and appears to be just fine. If there are any issues when the device is in circuit, I'll advise

Awesome product. No instructions to put the thing together and picture shows how to operate it. If you are smart enough to understand a buck converter you are smart enough to figure it out

I'm using this to drive 3 watt LEDs, and so far it's working well enough. There's no instructions, but it's a simple enough device that most people should figure it out easy enough. I'll probably buy more in the future.