Gearbox is an earth pony who runs her own little blacksmith and repair shop.  Gearbox is the youngest friend Belle has, but she is not only the naturally strongest mare Belle has ever seen but is considered to be the most intelligent individual as well.  Gearbox makes all of Belle's Mare Do Well gadgets and weapons, as well as provide medical aid when necessary.  Gearbox even helped set up the equipment in Belle's base.  Gearbox is highly intelligent, whose expertise in the fields of mathematics, physics, and technology rivals even Twilight Sparkle, and her expertise in electrical and mechanical engineering surpasses anyone in Equestria.  She is smart, yet you wouldn't know it at first glance due to her loud, obnoxious, foul mouth, and love for fighting.  Despite this, Gearbox has a good heart under her tough exterior and possesses a great imagination for inventing.  Gearbox cares for others' well being, and can be wise and insightful when she wants to be.  Gearbox speaks with an Irish accent.