Add a 8-1/2" Radius to your guitar's fretboard using the Yonico 13002 radiusing router bit. This bit has a radiused cutting height of 1-7/8" For fretboards up to 3-3/4" Wide. The bit features C3 premium micro grain carbide and 1/2" Shank. A unique way to add a radius to your stringed instrument's fretboard. These radiusing bits will eliminate the excessive effort required for using a sanding block. Tape the finger board to a perfectly squared board and slide along the router Table fence with the top of the bit's blade running at the height of the center line of the finger board. This will radius one Half of the board. Then flip the stock to radius the other Half. Yonico fretboard radiusing router bits come in radiuses of 7-1/4", 8-1/2", 9-1/2", 10", 12" & 16".