Genesis easy level system- can they be easily used on walls question

[what]

I purchased this system to use on large tiles for floors and walls.
When I bought the system I thought the bases would be flat but they are if fact quite curved which raises the tile some distance away from the bed (6mm) before tightening the red top.
There doesn't seem to be a flat base version available - only the universal base type
Whilst this appears to work for floors in my experience, are they suitable for walls? ( it does says so in the advertising specifications ).
I'm quite sceptical that the would work in a vertical situation, has anybody used them on wall?

 

[Dumbo]

I have they did work but I had flat Base version

 

[what]

Where do you get the flat bases from? I can only find the curved ones.

 

[Dumbo]

I used to buy mine from Hampshire tile warehouse . I say used to as I now use bright ideas which is a copy of Raimondi levelling system .

 

[what]

It's obviously a rubbish system - an expensive mistake