the tightening screws have to be very tight to hold a 1kg book in place. They let me down twice but they worked fine after a re-screw, so maybe It's my fault idn. And I have it the more vertical as I can get. When I got it, it was a pain to make it go to position. I think the paint got into a place that it shouldn't in the manufacturing process, because once I made it work properly, a little slice of paint came of.
On the good side, it is good looking and have a solid base.
UPDATE: After a couple of years gig after gig this thing is still working good.