Philip it is an electronic key safe that they key holder can send a code for in the case of an emergency.
that's a good idea, but i think an envelope sealed and signed by the key holder is secure enough.
Max9
you are right and i admit that my system is not ideal either, especially when i am out and about.
Max9 a combinarion lock usually has 4 digits. That's an increadible high amount of possible codes, no chance to guess them.
perhaps a combination lock with 6-10 digits attached directly to the belt? then you can call the key holder in an emergency and free yourself immediately.