The Atomic Sub-Frame Mask offers a new standard feature never seen or Seen Through" before in a Diving Mask. Atomic calls them Ultra-Clear Lenses. What makes Ultra-Clear special? Did you ever notice that Normal Dive Mask Lenses have a Green Tint to the Glass? To see this Tint, put your existing mask up to a piece of white paper and see for yourself. The Green Tint you see is the result of Iron Impurities left over in Lower Quality Float" or Window type Glass. That Green Tint Distorts True Colors and Blocks-Out some of the Light that Reaches the Eye.