Saint Laurent Occhiali da Sole SL M40 001 Nero/Nero Donna

Choosing the right size is essential for comfort and fit.
Glasses dimensions are expressed with three numbers, for example:

👉 50 ☐ 21 ☐ 145

Here's what they indicate:

• 50 – Lens width (caliper)
  The horizontal measurement of the lens, in millimeters.
• 21 – Bridge width
  The distance between the two lenses, or the part that rests on the nose, in millimeters.
• 145 – Temple length
  The length of the temples that rest on the ears, in millimeters.

🎯 How to choose the correct size

To guide you easily:

• Small face → caliper 48–50
• Medium face → caliper 51–54
• Large face → caliper 55+

For temples:

• 135 mm → compact fit
• 140 mm → standard fit
• 145 mm → wider fit

🔍 Useful tip

The easiest method is to start with a pair of glasses you already wear:

✔ Check the numbers inside the temple arm
✔ Choose a model with similar measurements

This way, you minimize errors and returns.