
The Janka Scale is a measure of the durability of a wood species to wear and denting. The higher the number, the harder and more durable the wood. It gives an indication of the suitability of various species to applications such as fretless fingerboards.
Note: my personal experience with Cocobolo would place it much harder than this standard chart indicates. Like any species, some properties are dependent on the source and location where grown, and may vary.