I've got a couple Magnum .75's. They scream on a 12X6, run great on a 13X6, and bog a little with a 14X6. for the money, the Master Airscrew is about the toughest (but not most effecient) for flying off grass, gravel and runway. APC's, especially the thin ones are very effecient,more expensive and break almost on a blade of grass. The APC wide blades are almost as hardy as the MAS props. Buy what works for you, it's only a hobby, but for most of us it's an obsession.