The greatest feat of grip strength ever.  No question in my mind.  I've been around the game a long time and I have seen a lot of things - this is out of this world.  When we built the Level 10 I never really thought anyone would close it.  It's so far past the level of strength of a CoC 4 or the GHP 9 that it's really hard to believe anyone's hand would be strong enough to handle the pressure.  You can see in the video how hard of a time Carl has just holding the gripper at a set while he posit