Rocktape RockBalls Twin Pack Precision Spikey & Smooth Trigger Ball Mobility Set RockBalls are agreat way to performself myofascial release with pinpoint accuracy. They aresold as a pair and feature a large spikey ball, a small smooth ball and an instruction book with release trigger points and mobility exercises. Best of Both Worlds Two is definitely better than one. The 3.5 textured ball and the 2.5 smooth ball give you two tools to break through tough tissues. Detailed Instructions Included with every RockBalls is our Movement Manifesto, which outlines the dangers of a sedentary lifestyle and features a multitude of corrective exercises and tissue release techniques. Conveniently Portable Corrective exercise can and should be performed anywhere and everywhere. Keep your RockBalls at home, in the car, or even travelling. Added Bonus: Movement Manifesto Every set of RockBalls includes a special Movement Manifesto, a booklet that contains valuable information to educate users on the following: How to use RockBallsDetailed movements and exercisesHelpful hints about best ways to use RockBallsBreathing and proper alignmentDifferentiating pain from discomfortA full reference section that will appeal to medical professionals interested in learning more about movement techniques Specifications One spikey ball 3.5 diameterOne smooth ball 2.5 diameterBoth are made of rubber Model91558477 Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-YJL official store