My first one had some kind of burr on it so threw it away and took out the other one. I have used it since last Oct.---finally replaced it the other day.
I was at a quilt shop the other day and commented about how long this one had lasted me. The owner said be careful they will ruin your mat??? She said if you really press down to cut that will ruin it? So far I haven't had a problem and my mat looks as good as new but I don't have to press hard because the blade cuts like butter.