Yeah, those are good. Barbell wrist curls behind the back are very good too. You can use a ton of weight. What I like to do is do something like the wrist roller or wrist curls regularly and mounting up the poundage and/or reps/sets. Then I follow each session with a dead hang for time pretty much immediately after. If while doing that my dead hang time doesn't decrease I know I am making some good progress. It's painful though
