Tiles are marked with nice big numbers, each in a different color. Water did come in, but it was very minimal. I just used alcohol wipes. Super cute slippers. An excellent product - pity it has to be bought from US, but Amazon do an amazing job! They slide right off once I put on shoes and walk. They are simply amazing. They came in a pack and a few didn’t work. Sony? What were you thinking here?I have a $40 Senso that sounds infinitely better. Had to mute myself “during competitive play” because my team mates couldn’t hear over the crackling.