Spring-operated penetrometer is used to measure compressive power of soil by pushing a floor and polished 1/4″ diameter loading piston into soil to a depth of .25″. Finish space is .05 sq. inch. Compressive load in tons per sq. foot or kg per sq. cm is indicated by studying scale on piston barrel. Most studying attain is proven by friction ring. Made from anodized aluminum. Allen wrench and plastic carrying case with belt loop are included. 6-1/4″ Lengthy.