I like your choice of jewelry.
I have a couple sets like that but only have a working key for one set. (The other set has a slightly narrower key slot and won't take the key that works in the first pair and I am not about to modify a key that works so well.)
Tower handcuffs and leg irons tend to be a bit temperamental and their keys vary a bit. Some of the keys are much too thin walled and will break easily. I have a few sets of Towers and they seem to have a higher percentage of problems than most.
This isn't self bondage, but my Jailer once put me in Chinese leg irons for a couple hours without any protection and stimulating turned to painful pretty quickly. Unfortunately for me, there was no way I could remove them and she does not check on me much when I am securely locked to something (which I was).
The Tower handcuffs in this picture have worked perfectly for years though we don't use them much. They make a lot more noise than most shackles.
