Cool product! You guys also might want to check out DigiFlex..... I don't have a link or manufacturer but we use those professionally with the advantage being you can train not only the flexors in your forearm but the intrinsic muscles of your palm. The DigiFlex offers the advantage of being able to work one finger at a time as well as thumb in each 'plane' of movement which is important because of the type of joint it is and the muscle attachments involved. You can save some money on the 'step up' equipment like IronMinds gripper by buying one that is too hard for you to press and simply focusing on an isometric 'hold' then progressing as your strength increases. Isometric incorporates more muscle fibers during repetitions and is VERY efficient at building strength. For a no-equipment workout, squeeze your hand, then squeeze your thumb and each finger in a pinch grip then walk your hand down into a martial arts fist moving one set of joints at a time ending with a 'hold'. for all these you then work your way up to being able to do a full 10 reps which is good for being able to build strength but my advice is to develop a routine starting with three set of 15, then 12, then 10 with the last one being all you can possibly do. Also, don't forget to stretch before and after as well as throughout the day to decrease soreness.
Shawn
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I know I can't hold the hate inside my mind
'Cause what consumes your thoughts controls your life
So I'll just ask a question
What if?
What if your words could be judged like a crime?
-CREED ('What if')