Having just bought two Shure SM57 mics from two different sellers, that were fake, I thought I'd share some of the differences.: 1. The mic should weigh 10 ounces 2. The top plastic grill should rotate freely 3. The body of the mic should be a smooth texture when you run your nail along its length. 4. Where the xlr pin locks into the mic, there should just be one round screw hole with a screw in, and below that one rectangular hole for the xlr to lock into. 5. The pencil case should have a texture to the material, not smooth. Hope this helps!!