RLens

RLens are contacts with temperature-sensitive diagrams of "R" and "L" printed on them. The alphabets become visible when the lens is out of the eye and disappear when worn. This feature is beneficial in two ways: you will always wear the correct lens & in-case you drop one; it will be easier to find it because of the visible lettering.

Source: yankodesign.comAdded: 26 August 2011