Hello Boatanchor members,I have recently acquired an old national HFS receiver and it needs a tuning knob...It is one like on an HRO with five windows and the numbers from 0-500 change when you turn it...It is approximately 4.75" in diameter and the shaft is a bit larger than 1/4".. I will gladly compeensate with cash or anyway you dictate....Joe in Okla. w5jdy