Jibs are any type of fixture which can be ground, buttered, or tricked off of. * Rail: A metal bar, either rounded or with a small flat surface, which a skier or snowboarder can slide across (called "grinding"). * Funbox: Similar to a rail, but wider with a ultra high molecular weight polyethylene (UHMWPE) surface. May or may not have metal edges. Compare Funbox, for skateboarding. Rails and boxes have many different shapes and sizes: straight, sloped, curved, or kinked.