(I did not buy it from skroutz even though I buy many products from here).
I put it on outdoor marble stairs after washing the steps and letting them dry. The next day it rained and they completely came off! Luckily I noticed it because if someone stepped on them, they would slip more than if I hadn't put them on! Additionally, they claim to have 5 meters inside, but one package had 4.90 and the other 4.80! Unacceptable!

Installation on an indoor store staircase because the storage is located downstairs. We now have much more security and comfort for going up and down.

It is exactly as described. I have had it installed indoors for about a month and it's working great.