This Fitness Mad Stability Cushion is an ideal tool for improving balance and posture; you can kneel on it or sit on it while exercising to increase the challenge of a workout to help build core strength and tone abdominal muscles. It's also great for using while sitting and working at a desk; as this cushion is essentially 'unstable' by simply sitting on it it keeps your core muscles working and your postural reflexes stimulated - effectively keeping you exercising while seated.;To use the cushion on a chair we recommend you use the cushion for 15-30 minutes at a time repeating at regular intervals during the day and so your muscles do not get overstrained. If you're looking for a greater challenge you can let some of the air out of the cushion to decrease the stability of the cushion even more or you can increase the air with the pump included. The nodules help to grip the surface the stability cushion is being used on and the anti-slip dots on the smoother side which is more comfortable for using when seated.As well as a posture aid it can be used for a variety of exercises for a full body workout the unstable surface makes the exercises harder by engaging your core muscles. You can sit kneel stand plank or perform push-up's with it.Diameter: 350mm.Colour: Grey.Material: Latex free PVC.Includes pump.Can be inflated or deflated to increase or decrease the level of stability.Can be used in pairs under each foot.One side with small anti-slip dots one side with nodules.WARNING:Remove from box and check for damage before use (a crease or fold marks are normal due to shipping).Do not use the cushion if there are any signs of damage e.g. a deep scratch gouge or holes.Do not overinflate or use high pressure hose to fill. Only use pump included to inflate.