These frets are 3/16 inch diameter stainless stell rods which slide into "open O" configured grooves from the side of the board. The are anchored below the surface with no visible apoxy. These round frets are exceptionally smooth to the fingers and never wear down. They are slightly lower to the board than "jumbo" guitar frets and are uniform and exact in height, allowing for very light touch, a greater dynamic range, and fast execution.