The Tonic trimmer I bought about 2 years ago does not suffer from the same problem as the Fisker's portable (12") trimmer I had used for years: the plastic track the blade slides in does not bow & bend, so it consistently makes a straight line. These blades last me about 3 months of typical scrapping use, less at Christmas or other intensive "project" time.
I only need to change these blades about every six months. Before buying these refills, I used a refill just from a craft shop and they dulled so quickly! It was ridiculous. This is a vastly superior product. I highly recommend it.
I've looked everywhere for these! How great to find them in one of my favorite places! I received them in good order and quickly! They've made the difference in my cutter and I am so glad I found them!