This is a pair of New Antique Bronze piano desk knobs which include the screws to attach them to the keyboard cover of your piano. These knobs are designed specifically for a piano. The dimensions of each knob is 5/8" in height and 5/8" in diameter.
Please choose the type of screw needed. Either machine screws or wood screws are available. If the screw comes in from behind the fallboard, then the machine screw is what you need.