The Harper Nylon Senior 2 in 1 Hand Truck combines the practicality of a hand truck and the added versatility of a four-wheeled cart. The frame is made of glass-filled nylon which offers a low weight reliable strength and durability. The Harper Nylon Senior 2 in 1 Truck will assist with a variety of jobs around the warehouse office garage or any place you need to move heavy loads.Replacement Pneumatic and Rubber tires are available for purchase (10" wheel with 5/8" axle bore