Kick into action with our Ninja Thinking Putty™. This putty will get stronger with every stretch! Train and endure to become the ultimate Ninja. Become a Ninja! Ninja Thinking Putty™ features a unique formula that builds resistance as you play. This amazing putty actually absorbs your strength—getting tenser and tenser with each stretch—to leave you feeling like a true Ninja. Thinking Putty® helps build hand and finger strength through a fabulous tactile play experience with unique, unexpected properties and provides relaxing, yet stimulating interaction for anyone with sensory integration issues. Thinking Putty® is non-toxic, won't dry out, and won't leave a sticky or slippery residue on your fingers, so it's great for stretching, molding, bouncing, tearing, popping and playing by kids and adults alike.