Fat Gripz EXTREME are insane. If you haven't mastered your lifts with the original Fat Gripz then you won't be able to handle the EXTREMES.
With a full 3/4 inch increase in diameter the EXTREMES push your grip and arm strength to the limit. Which means that they are not for everyone, only for those who want to get jackt arms and are willing to work seriously hard for it.
IMPORTANT MESSAGE: Please don't buy Fat Gripz Extremes (orange) unless you have been training with Fat Gripz Original (blue) for at least a few months OR are purchasing both together as a planned progression.