The Crankshaft is a combination of the Gascan and Fuel Cell designs but turned up a notch. Dual lens polaric ellipsoid geometry (2 lenses cut from a single toric shield) offers maximum clarity at all angles of vision with patented XYZ Optics. Three point fit frame design holds lenses in precise optical alignment while stress resistant and lightweight O Matter frame material ensures all day comfort.Metal Icon accents. Fits Medium to Large faces.