There are a bunch of brands 3M, Standard Abrasive, Norton, Merit and private labeled generics, buy the type best supported in your area. The screw on types work best, the Velcro doesn't hold securely enough, when it flies off the arbor is damaged, costing a new one.
What's also neat are the radial bristle brushes to replace wire wheels. I've got them in different sizes for the die grinder and the bench grinder. No more flying wire bristles! Even found itty bitty ones for the dremel