Tumbl Trak Blue Denim Cover Air Floor with White Line Down Middle, Velcro, and Non-Skid Material (Cover Only) Our Air Floor Covers are a lycra denim material on the top and red vinyl along the sides and bottom They also feature our Smart-Mat Technology that includes Velcro along the edges to allow for connecting of units and non-skid material on the bottom A 4 in wide white line down the middle makes it useful for practicing beam skills too Purchasing a cover at the time of your Air Floor purchase also extends your warranty to two years It is recommended to use Air Floor Covers with our non-Velcro Air Floor units