Materials: stainless steel Device Full Length:40mm/1.6inch Penis Tube Diameter:32mm/1.26" Above sizes is fixed,what you can choose is the Base Ring Size. Base Ring Size:40mm/45mm/50mm(1.57inch/1.77inch/1.97inch) Base Ring Options you can choose: 40mm ring(1.57inch) 45mm ring(1.77inch) 50mm ring(1.97inch) 40mm ring+45mm ring (1.57inch+1.77inch) 45mm ring+50mm ring(1.77inch+1.97inch) The reason I offer 2 sizes base ring is to let customer can has 2 sizes ring to try,especially good for the beginers because they are not sure which size would fit them the best. If you need other size base ring such as 54mm, you can choose the “customize size” option to place the order and leave a note to tell me the size of base ring you want. For customize base ring item, it cost more and takes more time for preparation,please understand.