The Groover Metal penis RingThis piece comes in various sizes:approximate measurementsSmall: 40mmMedium: 45mmLarge: 50mmXLarge: 55mmThickness 5mmDepth/Width 29mm This product is certified 100% Non-Magnate and medical-grade steel. Beware of cheaper products that are not solid surgical steel but chromed steel or poor quality surgical steel that contains Magnate. Magnate is the ingredient that makes steel rust. We will only include this endorsement on our 100% surgical steel products.