The unique design of the inner channel features Opro's patented ‘fins’ – slim rib-like structures – that are made from a special gel-like material that softens and becomes more fluid when placed in hot water. When you bite into these softened fins, they mould snugly around the teeth to form a perfect, highly retentive fit. The fins of the Gold mouthguards have been designed for the perfect fit as they follow the position and contours of the teeth.