The Sea Vision 2100 Mask has all the features you expect to find in a quality dive mask. The double feathered edge black crystal silicone skirt and wide split strap combined for a comfortable and perfect seal on the face. The mask has a one hand easy to reach nose pocket for ear equalization that even works well with thick gloved hands. Mask is designed to fit a wide range of faces, fitting divers in a weight range from 60-240 lbs. (27.2 to 110 kg). Mask is a low volume design and provides excellent peripheral vision. easy adjust buckles make adjusting the mask strap a breeze. The Sea Vision 2100 Mask incorporates a unique lens design using CR-39 hard resin, a light transparent plastic polymer material common in the manufacturing of eyeglasses. It has high abrasion resistance, in fact the highest abrasion/scratch resistance of any uncoated optical plastic. The Use of CR-39 in the manufacturing of dive mask lenses allows color to be introduced to improve the ability to see the true colors at depth without introducing artificial light (dive light).