I bought this knife because of the retractable blade. I take blood thinners and was looking for something that was less likely to cut me than a regular box opener. I wanted this smart design but it doesn't work for me. It's safer, of course, but it's uncomfortable and unstable in your hand. The blade does not penetrate deep enough into thick cardboard, so multiple passes are required to fully cut through. It's hard to tell exactly where the blade is, so the cuts are often off-center. The design makes it difficult to cut the tape around the edges (sides) of the boxes. Expensive. There are plenty of really good regular box cutters out there for the same or less money.