The i4 offers more vertical and horizontal peripheral vision than any other mask * Two tabs allows you to remove the current lens and replace or clean it with ease * The anatomically correct i4 mask system offers the best in comfort for all facial contours * The i4 is also tested at twice the current impact ASTM standards, the i4 is built for comfort and built to last * Designed with the ultimate comfort in mind, the i4 mask is the latest in anatomical facial fit * Movement is much easier to recognize and provides a clear visual advantage * Simply push on each interior tab arm, slide them forward and the lens is free to be removed