I bought 5 inch wheels rated at 1050 lbs. I use them under large garage cabinets that weigh nearly 500 pounds empty. Weighing in at 7-1/2 pounds each, these reels are massive. . The central core is aluminum with an outer layer of molded polyurethane. The wheel axle is 1/2 inch in diameter; Kingpin - 3/4 inch. I won't load them to the 1050 pound rating, but I can trust them to handle it with ease. However, Revain's packaging was unforgivably bad. The six I ordered were placed in a box along with air cushion plastic bags. Nothing held them in place and they slipped, knocking out the packages and breaking through the sides of the box. FedEx ended up packing them in one of their boxes, which arrived a day late with a note on a badly torn Revain bill. Fortunately, they are largely indestructible, otherwise they would be badly damaged. So five stars for the videos. -5 stars for the packaging.