A back ring is the part of a chastity device that secures the device to the user and prevents it being taken off easily. Male chastity devices are not usually one part, but are composed of two main parts that join together to form the completed device. These two parts are identified as the tube and the back ring. The back ring becomes a part that anchors the tube to the penis.
The back ring typically locates behind the penis and testicles and encompasses the whole lot in one go. To be effective and not allow easy removal of the chastity device, the back ring must be a good snug fit, but not essentially deliver pain, though this can be an option.
On most products, the back ring can be either a fixed-size or have a selection of interchangeable rings that prevents release while still allowing blood to flow to the penis. Back rings are generally available in standard sizes, such as 40mm, 45mm, and 50mm. The perfect ring should fit comfortably around the base of the penis and testicles without being uncomfortable. To be able to do this you need to be able to measure the circumference of this area and determine which size will give the best combination of fit and security. The best way to be able to achieve this to make a good measurement.
Measuring the area at the base of the penis and testicles involves using a soft tape measure to encompass circumference while holding the penis and testicles in one hand and out of the way- you may need your partner to help with this part. You then need to divide the measurement by the factor 3.14 to get the diameter. For example:
If the measured circumference is around 160mm, then divide this by 3.14 and round it down to get 50mm diameter. This means that you are most suited to a 50mm back ring.
If the measured circumference is smaller at around 125mm, then divide this by 3.14 and round it down to get 40mm diameter. This means that you are most suited to a 40mm back ring.
The ‘standard' sized ring is 4.5mm, which fits a penis and testicles circumference of around 145mm.
With this measurement complete, you should then select a chastity device that meets the right size, or comes with a selection of rings in that include your particular size.
Back rings come in three basic fitting types: Basic ring, hinged, and padlocked. The basic ring is a solid ring that slips over the penis and testicles to fit snuggly behind them both. The hinged ring has a snap-fitting, while the padlocked variety is hinged and locked in place with a small lock once it has been closed. A slight variation of this might be the spider web device which incorporates a hand-cuff style locking mechanism, that is released with a key.
Of these fitting styles, the padlock type is probably the best for beginners, but has the disadvantages of possibly catching on clothes. The hinged back ring allows easy installation, but could be removed by the user. The solid ring is used by seasoned user, and needs care when fitting it.