If you can close the 350lbs, your hand strength is definitely 'world-class'.
Heavy
Grip 100 --100lbs for beginners and warm-ups.Heavy
Grip 150 --150lbs
Heavy
Grip 200 -200lbs
Heavy
Grip 250 --250lbs, "The Grip Master"
Heavy
Grip 300 -- 300lbs, "The Gripper King"
Heavy
Grip 350 -- 350lbs "Monstor Grip"