First posted this on the RTYM side but actually might be better suited for the A4 due to the lack of velocity pads and finger drumming. Can adjust between about 25-45 degree angles. I would recommend tightening the screws that lock the teeth together after finding the right adjustment.
Looks good, reckon I might try one out! Do you get the impression that it will hold the gear well without falling apart? I’d be using it for a tinkering/sequencing perspective too (I saw your post on the Rytm threads and agree that it might not survive heavy finger drumming 
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For the UK buyers, here’s the stand on Amazon UK - Amazon.co.uk
Interestingly, when searching for under the “AmazonBasics” manufacturer, I found this stand - http://www.amazon.co.uk/dp/B000CKVOOY - which looks identical at about a third of the price, though wouldn’t like to comment on whether the build is good, but it has lots of good reviews!
Its really stable and not going to collapse or anything as long as you tighten the pivot points after you find the angle you like. Only issue I found was with using the rytm the whole stand would very slightly start turning If I was finger drumming (might just need better surface grip). For the A4 with just button pushes and knob turning it works perfect. keeps me from hunching over the desk and looks nicer too.
That listing does appear to be the same thing. Can’t go wrong with that price! I’ve ordered another since the ipad doesn’t have one anymore.
Amazon basics also makes that light up usb cable you see sticking out from the A4. Also very inexpensive but high quality. Warning it is kinda crazy bright for some people it may be too much. I think they look great though.