"This just makes life a little easier when drilling very hard porcelain tiles. You could get by without it, but the task is difficult enough & for the extra cost buy it. Just needs a flatish area for the sucker to fix, so you may struggle around window frames, etc. I wouldn't bother for ceramic tiles."
"Makes it easy to use particular sizes of diamond hole cutters on wall floor tiles with a free hand power drill. Stays stuck to wall very well and centers the bit for starting the cut. Would be even better if more sizes catered for."