Brio offers 5.25" Radius Wood Blocks. They are great for a variety of reasons. Spot-leveling frets and fingerboards, and if you're gluing frets they can be used a cauls too!Each Block is made of hard maple. Excellent for accurate radius work.

This listing is for the WHOLE SET, all 9 Blocks as below:

7.25", 9.5", 10", 12", 14", 15", 16", 17", 20"

For Shaping the Fingerboards use 80 through 220-grit
For Leveling frets: use 220 through 400-grit

When working on compound radius fretboards, simply change blocks as you progress along the neck.

These 5.25" blocks are also used for spot leveling, they can also be used as a radiused clamping caul when gluing your frets.

Dimensions are 5.25" (130mm) long x 2-3/4" (70mm) wide