Allway ARK is undoubtedly the best safety cutter I had for over ten years without any problems. It's definitely made out of high grade plastic and can take a lot of abuse, and is reinforced on wear points. I decided to do an upgrade so it could use standard knives for deeper cuts by removing the tab shown. To make the blade modification I just notched the blade with a grinder where it contacts the slide bar so the blade fits perfectly.