The first number corresponds to the lens size, representing the horizontal width of the lenses. For most eyeglass frames, this dimension typically falls within the range of 40 mm to 62 mm, offering a variety of options to suit individual preferences and styles.

Moving on to the second number, which signifies the bridge size, this measurement defines the distance between the lenses and quantifies the width of the frame's "bridge" that rests on your nose. Bridge sizes of eyeglass frames generally range from 14 mm to 24 mm, accommodating various face shapes and ensuring a comfortable fit.

Lastly, the third number relates to the temple length, determining the extent of the frame's "stems" as measured from the frame hinge to the back tip of the temple. Temple lengths typically span from 120 mm to 150 mm, allowing you to choose frames that suit your head size and personal comfort. It's worth noting that you may encounter a small square, rather than a dash, separating the eye size and bridge size on the frame, depending on the manufacturer's design.