Arnold Schwarzenegger built his arms up to 22 inches at the hight of his body building carrier. That is not a very realistic goal for the majority of us, but we can use his methods to build our bodies to the best of our maximum potential. One of Methods that Arnold used to build is arms were ARM BLASTER curls
In Arnold Schwarzenegger's book "The New Encyclopedia of Modern Bodybuilding "Doing Curls with an Arm Blaster - a piece of equipment that, unfortunately, you don't see very often today - is a very strict way of working the biceps that minimizes cheating. By using the Arm Blaster, you get the same kind of effect as with a preacher bench - no elbow movement at all and strict isolation of the bicepcs."
You can't really argue with the results he got!
Here is a workout you can do that incorporates Arm Blaster Curls