Round Penis ring: 1.4 inch /36mm - 1.57 inch/40 mm - 1.77 inch/45 mm - 1.97 inch/50 mm"
Internal width : 1.3 inch/33 mm
Material: High Quality Medical Grade Stainless Steel 316 L, no chrome plating, no rust guaranteed.
To ensure proper fit, measure the width of your cock (take that measure at the base). Once you know your diameter, you can choose the size that will fit you the most, by its size and comfort.