Sea vision's 2100 Series mask is a comfortable fitting low volume two window mask with enhanced down and side vision in a streamlined frame. Mask is equipped with swivel buckles and its skirt is made from Crystal Silicone the highest grade of silicone available. This lens is a non-prescriptive bifocal lens with a +2.00 power designed for the diver who is experiencing difficulty seeing close up objects like watches, camera settings and gauges, while also providing a means for clear sight at distances. These lenses are available in all SeaVision masks or most two window masks, and of course available in Clear, Color Correcting or MaxVision Filters. The Gauge Reader is the solution for the special needs of the diver over 40 years old. More specifically, the diver over 40 typically experiences presbyopia, which is the eyes inability to focus sharply on objects up close, such as gauges, watches, and camera settings. The lenses are + 2 only.