Humboldt 200mm Pocket Soil PenetrometerHumboldt 200mm Penetrometer Pocket type. The Pocket Penetrometer is designed as a lightweight instrument for classifying cohesive soils in terms of consistency, determining the approximate unconfined compressive strength and the evaluation of shear strength using the penetration principle. For use by field personnel to check visual classification of soils. Verifies whether excavation side walls require shoring, based on OSHA cohesive soils