Balsa Strop is mounted on high-quality aluminum with 45-degree bevels (Edge Pro form-factor) and color anodizing: graphite gray, black, deep ruby red, ocean blue, emerald green, sepia orange. Different colors of blanks will help to avoid mistakes of using wrong grit. The thickness of wood is approximately 3 mm, the thickness of aluminum blank is 5 mm.
Balsa is the softest and lightest of all commercial woods - nothing else comes close to it. Balsa keeps its flatness better than leather and prevents the blade becoming convex when used on abrasive compounds.
Working with wood is similar to working with leather. You will not be able to fully remove the compound after applying it to the strop. If you want to change compound, consider buying an extra strop.