6 Base Curvature - The base curvature corresponds to the curve of the lens. The higher the number, the higher the curve. 6 base styles have a “flatter” look. 8-9 base curves hug closer to the face.
The frame measurements of sunglasses can vary dramatically and change the look just as dramatically.
The first number measures the Lens Width, the second number measures the Bridge Width and the third number measures the Arm Length.
So for example a 55-12-143 frame measurement means...
The Lens Width is 55mm
The Bridge Width is 12mm
The Arm Length is 143mm