Can be stainless steel or plastic and are usually used in a D/s situation. Rather than try to describe the process, I've sent a link... https://thrillofthechaste.net/2015/11/12/queens-keep-official-review/
I've been locked in a Queen's Keep for seven months, which limits my options. The key lives on my wife's favourite charm bracelet which never leaves her sight.
Hope this helps Rick
