CT-102 has a porcelain wheel and a serrated stem. These casters were commonly found on a variety of types and styles of furnishings in the late 19th and early 20th centuries. The wheel is 1 1/8"in diameter and the stem is 1 1/2" by 1/4" in diameter. Cast iron fork will support up to 150 pounds per caster. When determining the weight load of your furniture, please remember to include the weight of any persons or items that may be using the piece. No socket is necessary for installation.