This Babolat RPM Team 1.25 12m Set is a great choice to not stress the arm muscles. The technology of micro air bubbles is injected into the string, which increases flexibility for greater comfort, without reducing the durability. Although constructed with air bubbles to soften the feel, RPM Team is actually one of the firmest Babolat strings tested in our string lab. This is perfect for big hitters who don't like having to worry about overhitting. Play your best tennis with the Babolat RPM Team string.