Non polarized yellow lens round square shape clip-on sunglasses range in size from 50mm to 58mm widths. You can usually see the size of your prescription glass frame above the inside nose bridge in very small writing. You can also take a millimeter ruler to measure one lens of your glasses from the outside edges to get the right size. 

Please Note: Pewter frame is the standard color frame for all clip-ons. We usually only get one gold brown frame per box for each shape clip-on sunglass, which is why most sizes in gold/brown show out of stock when selected.