Fits with Bearing: The size of the bearing the bore adapter is designed to fit into.
Inside Diameter: The distance across the center hole, or bore, of the product.
Material: Describes what the product is made from. Plastic, aluminum, and diecast are softer than steel and cast iron.
Shoulder Length: The size of the shoulder on the bore adapter. When assembled into a bearing, this is the distance from the edge of the bearing, to the edge of the bore adapter.