There are frame width, bridge width, temple with and bridge location that you should take into consideration when you want to buy a pair of glasses. Frame width should be suitable for the size of your face. They range from narrow faces to wide faces. But most of us have medium faces. Bridge width can help determine the fit too. if you have close set eyes or a narrow bridge, you'd better choose the number which is between 15mm to 18 mm. as to the people who have a wider face, the number should be 18mm to 22mm. The temple length vary from 135mm to 150mm. usually the small faces will choose a temple length that is 135mm. Bridge location also plays an important role in choosing a pair of suitable glasses. If the bridge of your nose is higher on your face, you'd better choose frames with a more arched brow line and a lower bridge such as Jack, Sam and Dash. If the bridge of your nose is lower on your face, you'd better choose Gretta, Reese, Hugo and Tracy.