The Double Wall Fabric is a three-dimensionally woven structure whose two base fabric are interlinked with hundreds of thousands of spacer threads. Some of these threads may fluctuate insignificant in length causing the appearance of small dents (diam. approx. 1 cm) when the product is inflated. Most of the dents disappear after the product is used several times under a high air pressure. The ‘unknotting’ can be heard by a ‘plop’ sound. You can fasten this process by using a higher air pressure than you would normally use during trainings. The dents do not affect in any way the qualities and unique properties of the material, they are cosmetic characteristics of the Double Wall Fabric.