These are the same blades you buy in your chain store or LQS for big $'s because they're packaged for us quilters. The ones at HF are sold for carpet cutting. My husband was a machinist & he says metal is metal, they might not be polished quite as well, but at approx dollar apiece (or less if you get them on sale, in Oregon, lol ) how can you go wrong? I've been using them for a couple of years and only ever found one that I couldn't use from the getgo, just toss it over your shoulder like Eleanor Burns and get another one out. lol
They fit any 45 mm rotary cutter you may have. I just checked and they're still on sale for $1.49
http://www.harborfreight.com/pack-of...des-97642.html
Happy cutting!