(Also available in UK from Amazon) They are indeed. I think visual range is necessary, to know when the dog or person being trained has...
After doing a bit more research, I think is a re-purposed dog collar based on this high-end one:...
Source: https://www.etsy.com/uk/listing/177130799/stainless-steel-shock-collar-bdsm-bonds You'll all love this then - very much not a cheap dog...
I know this is an old thread, so people will have already worked out by now why combination locks are not a good idea. The thing about chastity...