Zottman DB curl, old school and another exercise known by other names: Zotterman/Zott/Zotter. I call it Zotterman, which also may be incorrect. . As with any training systems, which can be know by other names.
Found a few golfer and bowlers like this exercise. Yes, some golfers and bowlers do train with weights, moderate to heavy. Including lower back and ham work. Tiger Woods, Greg Norman, etc. comes to mind. And surprisingly some people with advancing or mild forms of arthritis have benefited, with regards to hand and wrist function. Not a cure for pain of course, but does seem to allow a certain reduction of discomfort.
Zotterman curls can affect the biceps, grip, wrist, forearms and even the elbows in a positive way. Usually done with a slower cadence and with a light to moderate weight. Usually a rep range of 8-12. Hard to adapt to his style movement for a lot of guys. But if taking your time to learn it, than its worth your while. The negative part (lowering the DB) will need strict attention when first learning how to do this exercise. The negative phase is important.
Good Luck.