Advantage: The shape is more in line with the physiological structure of the human body. Used as cock ring (on the root of cock) There are 6 sizes optional as below. A1: 38*45mm=130mm A2: 44*49mm=146mm A3: 51*56mm=168mm A4: 42*49mm=143mm A5: 48*54mm=160mm A6: 53*59mm=176mm The number after “=“ is the circumference. Use a string around the root of your cock to measure the circumference, (measure tightly)always choose a smaller ring than your measurement circumference. For example,if your measurement is 135mm,then should goes with A1 option. Customize service is optional,various people has various size,the above 6 sizes can’t fit all people,so if you need other size,choose customize size option to place your order.Customized curved oval cock ring is bent by a round ring actually.For example,if your cock root’s circumference is 198mm,I suggest you reduce 10mm circumference,and give me customized circumference 188mm,then I will use 60mm diameter round ring to bent it,to achieve the curved shape. (60*3.14=188,diameter *3.14=circumference) Customized ring’s thickness/gauge is 1 thickness constantly,not like this existing curved oval ring (one side thin/6mm,one side thick/12mm).You can only select 1 thickness from 6mm,7mm,8mm,9mm,10mm. For customize size,you can specify the circumference or specify the diameters like the above existing size.