That's a shame. I have an older version of these rulers. I called them about slightly slivered edges on mine from my use. Their claim is that that won't happen because they are made of a polycarbonate material. So, I wanted to tell them about it and they didn't believe me. They wanted me to send them a picture and I never did follow through as I was annoyed by their tone and I wasn't good at emailing pictures then. The slivers are just slight on the corners so I stay away from the corners now and no longer hook them together anymore (to make one 6x24" ruler from the two 6x12") to avoid cutting near the slivered area. Quite expensive to have trouble with the corners and to not be able to use it in the size I intended, I think!
On the plus side I love how they grip the fabric and how you can slide the fabric under them till it bumps up against a yellow strip that I've set to my desired cutting width. So I use them very frequently when I need a 6x12" ruler.
Currently, I just ordered the 24" slidelock ruler and can't wait for that to come in. Its getting a ton of positive reviews here on our site.