Dear Customer, thanks for choosing Firmoo. This frame S3500 has a size of 51-19-140(Medium). Choosing a perfect frame size online can be tough sometimes, here's what we can do for you: First, kindly check how to measure eyeglasses size and find the perfect size. You can also check the numbers on your old glasses that look like 50-18-135. The 1st is the width of one lens; the 2nd is the bridge distance, and the 3rd is the length of the temple piece that goes behind your ear. If your old glasses are too big/small, you can go up/down 1-2 millimeters (example 50 to range of 48-50). I hope this is helpful. Please take care and stay safe!