Optical frame sizes are represented by three numeric designations: eye size - bridge - temple length (for example 65-15-120). All measurments are in millimeters.

A Measure:
The horizontal width of each eyerim.

DBL Measure:
The bridge, or distance between the eyerims.

Temple Length:
The distance from the hinge screw to the end of the temple tip.

Petrol also list two additional measures to help you assess how each frame will fit.

Width:
The total horizontal width of the sunglass frame front.

Height:
The vertical depth of the sunglass frame front.

BASE CURVES DESIGNED WITH YOU IN MIND

Higher lens base curves allow for more "wrapped" frame styles, which help prevent unfiltered light from leaking-in at the temples. For some manufacturers, deeper base curves = increased distortion. Not Petrol. Our precision-engineered, injection molded lenses deliver deep wrap styles without sacrificing optical clarity.

Base Curves and "Rx-ability"

6-Base:
A spherical lens with a flatter curvature ideal for prescription lens insertion.

8-Base:
A spherical lens with a more pronounced curvature, but still "Rx-able" for wearers with mild to moderate corrective lens prescriptions.

9-Base:
A toric lens shape (cylindrical instead of spherical) requring a highly advanced lab for prescription lens production.