Ididn't purchase this item myself, I borrowed it from a friend. I tested it out when I put down ceramic tile in my kitchen. Without going into great detail let me just say "WHAT A PIECE OF GARBAGE". THIS HAS GOT TO BE THE CHEAPEST IMITATION OF A LAYOUT TOOL THAT I HAVE EVER SEEN. Take whatever money that you would spend on this and by a good tile installation book and straight edge. If you could rate items in negative values this "tool" would take top honors.