The Janka hardness test provides an object method to compare the hardness of various wood flooring materials. It involves measuring the force required to embed a 11.28 millimeter (0.444 inch) steel ball into wood to half its diameter. This method was chosen so that the result would leave an indention 100 square millimeters in size. It is one of the best measures of the ability of a wood species to withstand denting and wear. It is also a good indicator of how hard a species is to saw or nail. The harder the wood, the longer it lasts and holds up to wear. The following is the hardness of the woods carried at Metro Flooring.