Male Chastity Devices
Male anatomy makes chastity somewhat easy. A male chastity cage often involves a metal or plastic enclosure that contains the penis. As the penis tries to become erect, it is unable to due to the walls pressing against all sides of the penis. If the fit is proper, it will prevent the male from ever getting hard inside the cage. Additionally, this prevents the male from touching and/or stimulating the penis, preventing an orgasm from occuring via penile stimulation.
In addition to there being a containment for the penis, chastity cages also come with a base ring that goes around the shaft of the penis and the testicles. The penis container often integrates into this base ring to allow the placement of a small padlock, and also prevents the male from removing the cage entirely since the testicles are trapped between the base ring and the container for the penis. This also prevents the male's penis from becoming longer and extending the cage.
When a male is locked in this type of cage, it is very securely attached, and he will need the key to the lock.
Metal Cages
Metal cages are often made of stainless steel and are seen as less escapable than plastic due to durability. However, the cage can become quite heavy and obvious to the wearer. This is sometimes seen as a positive to enforce the submissive aspect of a BDSM relationship.
Plastic cages
Plastic cages are much lighter for the wearer. Plastic is less durable, but still very difficult to remove, as sensitive organs are involved, which removes the option for power tools or other methods of removal. One complaint of plastic cages is that moisture can accumulate, so precautions must be taken to avoid harboring an environment for bacteria.