Emopeak Super Gripz Think Bar Grips Turns Barbell, Dumbbell, and Kettlebell Into Grips for Bar Training and Muscle Growth. Strengthen Your Forearm, Biceps TIME-TESTED METHODS, NEW SCIENCE - Science has now confirmed what athletes and bodybuilders have known for decades - that using a thicker diameter bar causes much greater muscle activation in the arms which leads to incredible size and strength gains.