A Pocket Concrete Penetrometer is a compact, lightweight, spring-loaded testing tool designed for quick field or laboratory evaluation of the initial set (hardening) of concrete mortar or grout. It measures the resistance to penetration, providing an estimate of compressive strength in psi (pounds per square inch). It’s particularly useful for on-site assessments during construction to determine when mortar has reached a semi-hardened state where it can no longer be easily worked.