Pain is a hand-sculpted artisan keycap made for mechanical keyboards which can be used as a replacement for any key. It is designed to fit comfortably in the escape row on cherry keysets and should work with any MX style switch.
Unlike most keycaps, Pain features an opening in the back left allowing you to string it from a keychain, a necklace, a bracelet, or anything else you like.
If you're curious about the sculpting process and seeing how it's evolved over time you can view progress shots here.
This Listing is for the colorway "Terminal Green" which is meant to match the green used in GMK Terminal as closely as I could manage.