The most important innovation since the introduction of silicone masks is Bi-silicone Technology. In all of the current masks on the market, the skirt is made of rubber, silicone, or another medium-hard elastomer. All of today’s masks are a compromise between the need of a hard material to provide support to the frame and lenses and that of a soft material to adapt to the contours of the face and provide a good fi t. Until today, manufacturers have been forced to look for compromiseable solutions, since the skirt was made of a single material.