Sweaty mitts are a climber's worst nightmare; there's nothing worse than nearly finishing a route and finding yourself inexorably sliding off the wall.
The DMM chalk ball dries out clammy hands, improving your grip on the wall. Fitting neatly inside chalk bags, it comes without the mess of loose chalk.
It's for this reason that chalk balls are mandatory at most climbing walls. Just give your chalk ball a friendly squeeze before reaching for the next hold.