4 Base Curvature - The base curvature corresponds to the curve of the lens. The higher the number, the higher the curve. 4 base styles have a “flatter” look. 6-9 base curves hug closer to the face.
100% UV Protection - The sun is harmful to our bodies and eyes, all Spy lenses are 100% UVA/UVB/UVC protected so you can worry about your goggle tan while Spy shields your eyes.
Arc - Accurate Radius Curvature lenses are injected in a unique tapered shape to provide optically correct, distortion free viewing at all angles, ensuring against discomfort and eyestrain.
Spectra - Spectra lenses contain multiple layers of mirror for a look that is as unique as it is effective in full sunshine. Spectra mirrors keep bright light toned down and lets your wandering eyes go undetected.
These measurements include the width of the lens, the width of the bridge and the length of the arms measured in millimeters.
For example, a 59-15-135 frame:
1) Lens Width - 59mm
2) Bridge Width - 15mm
3) Arm Length - 135mm