I'm not sure what the official name of the exercise is, but I saw a body builder named Victor Martinez performing it on Youtube. You move a cable pulley down low, then curl with each arm. Here's a link to the video.
Hmmm, I’m not sure, just looks like a variation of a curl, it looked like they were doing hammer curls with it at one point. I primarily do a session of hammer curls and then preacher curls.