[Package Includes]you will get 12 pieces of star knob 1/4 inch. Before making a purchase, T track knob threading is 1/4 inch in diameter , suitable for 1/4-20 rod. [Well Made]Each 1/4-20 knob has a brass insert that molded in a plastic knob. The thru knobs have enough threads that are intended to thread on a bolt to clamp them together. [Star Shape Design]This Through Hole Knob are Star Shape Design, Great for comfortable hand grip, accord with ergonomic design and plays a non-slip effect without scratching your hands. [Handy Design]The bolt can go all the way through the tightening knob, and stick out the top to give plenty of adjustment range, when the screw happens to be longer than you need it to be. [Wide Application]The screw-on clamping knobs fit for routing jig, saw fence, drill press, lathe, fixture which requires a 1/4-Inch 20 female thread.