The Power Balls are the ultimate training tools for working grip strength while doing pull-ups. The 4" diamiter balls provide a radius for open hand training. From pinch strength to core exercises the Power Balls provide more advanced rock climbing training options than your standard hanging tools.
Sold in pairs.
Featured in the Climbing Magazine 2013 gear guide review.
http://www.escapeclimbing.com/power-balls-in-the-2013-climbing-magazine-gear-guide/