I designed this for a single edge razor. It uses 3 3/8' x 1/8" round magnacraft rare earth magnets glued into holes on back. (I use brass pick to help insert them). Once they are glued, they can be placed on any metal (magnetic) surface and hold a single edge blade ready for use. Helps prevent cuts while handling a razor blade. Care is always required when handling a razor blade but I am just trying to help prevent cut fingers as I use this daily.