The horizontal diameter of the full frame, including both lenses and the bridge.
The horizontal diameter of one lens.
The width of the bridge between the lenses.
The length of the audio temple from the frame to the tip.
If you already own a pair of well-fitting glasses, you may be able to find their dimensions printed on the inside of the temple.
For example: 54-18-140
Because all glasses have slightly different shapes and sizes, if yours are 2-3mm bigger or smaller than our measurements then soundcore Frames should still fit you.