NuActiv Ab Abdominal abmat Exercise Trainer with Foldable Tailbone Protection Anti-Slip Pad The anti-slip pad connected to the abdominal mat protects the tailbone and prevents unwanted bruising and skin burn. The additional thickness on the anti-slip pad creates greater back extention for your ab workouts. The anti-slip pad will make your WOD times faster by not having to adjust the ab mat due to constant shifting. The abdominal mat and tailbone protection pad combined is comfortable and ergonomically correct for the back The foldable & lightweight design makes it portable for easy storage or travel. One size fits all.