This is a high quality solid aluminum knob that looks absolutely professional and classy. It is not as heavy as some knobs, because of its size, and the bottom portion was made a little thinner for me. This knob is .59" in diameter and .59" tall and has a set screw for mounting to any type of shaft. The shaft hole is made for 1/4" shafts. Each quantity is for 1 knob. The picture is for illustration of the knob.