Review on Airlfa 45mm Rotary Cutter Blades 10 Pack - Perfect Fit for Fiskars, Olfa, Martelli, Dafa, Truecut Replacement - Ideal for Quilting, Sewing, Fabric, Leather, Paper, Cloth, Card - Ultra-Sharp and Long-Lasting by Summer Hendricks

They're nice and sharp. I've used about 4 of these so far and cut a ton of quilted cotton for masks and they're holding up well. So far 4/10 have been good and I hope the rest will be good too. I was concerned because these off-brand blades are usually either good or terrible, so I wasn't sure what I was getting into. I will buy them again when I get to the end of this pack. My only complaint is that they are a bit oily and stick together in the packaging which can make it difficult to separate. Definitely not a deal breaker, but watch your fingers when you pull them out.