The mounting bracket is tightened by hand using the button at the end of the screw (black, visible below the support on the photo of the article). It took a little fist to put in place (close enough for the 2 pieces of the mounting bracket).
It looks to hold much, but I regret it as easy to disassemble without tools.
The lamp fits into a ring, and one second screw is tightened by hand to fit into place. This helps her out when the bike station.
We'll see over time if it is resistant to many assembly and disassembly.