The Pocket Penetrometer is a spring-operated device with a 1/4in (6.4mm) dia. loading piston that is pushed into the soil up to the calibration groove which is machined into the piston 1/4in from the end. The permanent, direct-reading scale on the piston barrel of the penetrometer reads approximate unconfined compressive strenght in tsf or kg/cm.

Pocket Penetrometer also called a hand penetrometer is constructed of stainless steel. It is a simple, lightweight, handheld device made for instant estimates of the unconfined compressive strength of cohesive soils. Although it does not replace laboratory Unconfined Compressive Strength Test Systems for the determination of unconfined shear strengths, the Pocket Penetrometer is a valuable tool for providing approximate values quickly.