A concentration curl allows you to isolate your biceps, or specifically the brachialis muscle. For this exercise, use dumbbells. You'll also need a flat bench.
1) Sit at a flat bench with your feet flat to the ground and have your legs spread out a bit.
2) Curl the weight upward toward you. Keep your upper arm still, only moving your lower arm.
3) Lower the weight slowly down. Get back to the starting position Repeat.
Hold bicep contraction for max gains. Try to isolate and use only biceps to make the moment.