When searching for a reliable and durable solution to your caster needs, consider Service Casterâs Series 20 square stem polyurethane casters. The square stems are designed to be bolted or riveted onto the inside of angled iron legs or against any flat surface.Supports a total weight of 1,200lbs (300lbs/per caster).The Service Caster Series 20 is ideal for light and medium duty material handling, carts, equipment, and shop projects.