Lightweight, direct-reading penetrometer gives instant information for classification of cohesive soils on site or in the lab. Use is required by OSHA for trenching and excavation inspection. The spring-operated device has a 1/4in (6.4mm) dia. loading piston that is pushed into the soil up to a calibration groove machined on the piston 1/4in from the end. The permanent scale on the piston barrel reads approximate unconfined compressive strength in tsf2 or kg/cm2. An indicator sleeve retains reading after piston is released. Spring is calibrated and plated for rust resistance. Complete penetrometer weighs only 2oz (57g); dia. is 3/4in (19mm) and length is 6in (152mm). Adapter Foot Attachment of 1in dia. has sixteen times the piston area, for soft soils.