We'll explain it to you
All frames have sizes
CALIBER, BRIDGE WIDTH AND ROD LENGTH
LENS DIAMETER, or its amplitude; it is used to understand how LARGE A LENS is, and what the effect of the glasses will be once worn.
SMALL DIAMETER (e.g. 47-48)
identify glasses with small lenses, suitable for small or women's faces;
LARGE DIAMETER (e.g. 51-53-55)
on the other hand, it is more suitable for large faces or for drop-type glasses.
BRIDGE WIDTH, ie the distance between the two lenses; how the glasses will fit on the nasal septum
LENGTH GOING FROM THE END OF THE FRONT TO THE REAR OF THE EARS Relative parameter as it is possible to work on the curvature of the rods to adapt the fit.
For example, if the model you have chosen shows the size "57-14-140"
it means that it will have:
CALIBER (LENS DIAMETER) OF 57 MM OR 5.7 CM
BRIDGE (DISTANCE BETWEEN THE LENSES) OF 14 MM OR 1.4 CM
AUCTION (LENGTH OF THE AUCTION) OF 140 MM OR OF 14 CM