flap disc for surface rust removal?

I dont have one on hand since im using my phone. But they look kind of like a sponge but their sort of hard and coarse. My local lowes sells them next to all the sand paper and stuff. Wagner makes the tool called the paint eater and it looks kind of like a router for wood working but uses the 4 1/2" discs like a grinder. They may call them something other than paint eater disk at other stores. Theres one with an arbor sticking out that fit in a drill but unless you have alot of time id go for the grinder lol