These drivable, steerable dollies are designed for maximum versatility and durability. Whether you're moving your sled on grass and dirt, or on a paved surface like concrete or asphalt, Power Wheels Drivable Snowmobile Dollies help you move your sled at speeds up to 5MPH. The set includes two ski dollies with cotter pin wheel assembly and a track dolly with a caster wheel for non-motorized use. Drive or slide your sled into the shop, up a trailer, or reverse into tight spaces for storage. Improved design incorporates a 31 percent wider wheel base for increased stability. two-year warranty.