Here is a nifty gadget that helps you build strength in your hands. The Hispox Hand Grip Strengthener has adjustable resistance from 22 to 132lbs. It is not only great for athletes but people who are recovering from injuries. It has a 2.5mm carbon steel spring. You can adjust resistance with the knob.
This tool measures 5.9 x 4.33″. It has an ergonomic design.