Descriptions: This item is made of stainless steel. The cage and ring are locked together with the lock. Once the lock is locked there really is no escape (unless you have the key). Features: Cage size: as picture The maximum diameter of dilators :8mm, It`s total length : about 150mm It`s effective length :about 135mm. no through-hole. Size 3 size for choose based on inner diameter of the clamp ring 1.57 inch/ 40mm diameter 1.77 inch/ 45mm diameter 1.97 inch/ 50mm diameter Base ring size measurement and choose method Take a inelastic line to surround the root of penis (the place is close to the belly, behind the scrotum), and then measure the length of the line, which is the perimeter, and the diameter equal to the length of Line divided by 3.14. Finally choose the base ring size near to the diameter. To avoid injury or aggravation of pre-existing conditions, this product should not be used on bruised, swollen, or inflamed areas including skin lacerations. Discontinue use immediately if irritation or discomfort occurs. Cleaning: Use a mild soap and soft type brush (toothbrush) for cleaning.