Very high quality tool from dspiae that absolutely feels like the premium product you paid for. The only problem with it in my opinion is that the rail that the sanding part slides on could be more stable. The stability wont be a problem as long as you dont try to sand too fast but for over 50€ I expect this thing to be perfect.
Also most people will never need this thing so I would not get it unless you really are sure that you will need it.