Found a few on ebay that where nicely made(for twice what you can make it yourself) but it gives a good idea of how to make a secure one. This one can't be removed or turned off without the key to the collar. On ebay for $800, can make it yourself for less then $400 (Strict Leather premium locking collar$40, Dogtra 1900NCP $250ish, And a couple SS Acorn nuts) One made from a petsafe little dog trainer. And the Big Dog version, Both of these can easily be turned off with a push of the button. No fun there!