Preacher Curls force strict form and allow Isolating the Arm Flexor Muscle Group without wasting energy maintaining full body stability. Use a Straight Bar on Preacher Curls to train all Flexors in one Movement, (Biceps, Brachialis and Brachioradialis). Reverse Curls on a Preacher Curls Bench are Superb for Isolating the Brachialis-(the Golf Ball Shaped muscle on the Side of the upper arm). Opt for an EZ Curl Bar on Preacher Reverse Curls and include them in every Bicep Workout. The Brachialis pushes up the Biceps Peak, Builds the Brachioradialis developing dramatic Size, Thickness, a Higher Flexing Peak and overall Bigger Arms.