A popular type of chastity device for men is commonly referred to as a chastity cage, penis cage, or chastity tube. They are almost exclusively used as a sex toy and in BDSM play, and may enclose a man's penis in order to make an erection uncomfortable or impossible if the man becomes sexually aroused, and prevent sexual intercourse, masturbation, oral sex involving the wearer's genitals and some other forms of sexual activity. A chastity cage may be combined with toys such as a shock collar or ball crusher.