We offer 3 sizes for the AKO motorcycle eyewear: 133mm, 137mm and 145mm. Follow our advice to know the size adapted to your face: Take a pair of glasses you already own (prescription or sunglasses) Place it on the edge of a table Using a ruler or a tape measure, measure the distance between the two screws of the temples If the screws are inaccessible, measure the distance between the axes of the temples Now please choose the AKO frame that is closest to your measurement in millimeters. Example: your measurement: 132mm = model 133mm Springfield your measurement: 135mm = model 137mm Lincoln your measurement measurement: 143mm = 145mm Flagstaf model View Larger Image