The HK2 Handcuff Key from TIHK is one of those things that you’ll likely never need but it’s good to have on hand just in case. It’s a tiny tool that clips to your belt loop or any other handy thing you chose. It’s small size makes it easy to hide and use when necessary. The universal key should work in most handcuffs but you should definitely practice in as many different handcuffs as you can because, you know, practice makes perfect. Get a pack of 2 for $12.