The corrective lenses with Universal Optical Frame can be used with numerous single lens masks. Available with a frame and pair of same diopter lenses -2.0, -3.0, -4.0, -5.0, -6.0.

The frame is designed with flexible 'wings' to allow insertion into numerous designs of  single lens masks - it may also fit the 'odd' twin lens masks. The frame is supported by the flexible 'wings', and this is designed to fit snugly inside a snorkelling mask, and is fully removeable.

The Tusa Optical frame is pictured inserted inside a Mares One/Pure Vision mask to illustrate how it is 'used' in a single lens snorkelling mask.  The optical frame is less suitable for use in single lens masks which are frameless/low volume, compact designs of mask.