The Smedley spring-type dynamometer has been used successfully for many years to measure grip strength. Adjustable handle comfortably accommodates any hand size. Unit is calibrated for kilograms which is over 220lbs.
Lightly used and everything works as it should.
New these uses are over well over $200 - https://www.orthocanada.com/en/smedley-dynamometer
Grip test / popat / fire/ police / personal training