Rings are a great deal thicker than bands, in my experience. My first wedding ring was 6mm wide by about 3mm thick. In white gold. That little nub in the photo wasn't nearly thick or strong enough to cut that. I'm thinking they meant banding like is used on boxes. Even steel banding is pretty thin, usually under 1mm. I've cut that with scissors a couple of times.Not a strong endorsement of it's reliability, I wonder if Gerber makes one?