This is an 11" diameter steel pulley that is ideal for use as the bottom/base of a steampunk industrial lamp. The center hole is tapered, starts out under 1/2" diameter, ends up over 1/2" diameter, sooooo buyer could drill out to exactly 1/2".  The V groove would have originally used a 1/2" to 9/16" wide belt, The only markings on the piece is the number 630493 cast into one of the spokes.