In principle, the previous speakers have already mentioned everything. The only thing I might want to give to a tip, you should very well make sure that the hole spacing is respected exactly. Even a game of about 2 - 3 mm (which can easily happen in the "softer" joints) affects - because of the tension thus created - noticeably to the simple replacement of the paper towel out. However, what has been missing me as a tip and therefore a star is deduction that you should just not drill on the joints. Because normally you try so most holes (except for very serious things such as wash basins) to make in the joints due to the optics and that one no longer than necessary drilling in tiles. However, I can only advise to drill directly into the tiles in this holder! Background is that's only about the wall bracket 2cm high and thus I had the phenomenon that the bearing surface for the wall bracket was too low and he easy game had (at the bottom of the wall mount), after tightened the screw. So, drill into the tile and therefore one has to but smaller area a 100% flat bearing surface and the wall bracket is straight.
For this to be a star deduction, may well be a bit fussy but when Zewa Holder for about 40 euros I expect that is thought along.