The Paw Pods are made from a firm yet flexible PVC material with an air-filled chamber. The Paw Pods are shipped inflated. Adjust the balance challenge by changing the amount of air inside each pod with a needle pump (not included) You can also change the difficulty level by using the Paw Pods placed with the flat side down (less challenging) or the dome side down (more challenging) The FitPAWS Paw Pods feature sensory bumps on top for neural stimulation and grip capability. Place under your dogs feet for advanced balance training, core strengthening and stacking training for show and performance dogs. FitPAWS Paw Pods can also be used for improving weight bearing issues for individual limbs, another great tool for canine rehab practitioners.