Big fan of the hyper core attachment. Works very well for a back extension, doing GHDs definitely is not an optimal position but it does put you in a position that makes the excercise fun. I even use this is as a preacher curl pad while sitting on the bench, if you are short you may need a child's booster seat for the exact position. Only downside is how unwieldy it is to move, but worth it in the end!
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