If its gonna come away when caught, you gonna lose it. More holes in the collar, tight fit. Job done. Never had a slip since adding more holes. The more stuff hanging off a ferret, the more chance its got of getting caught up or disturbing the nets.
I intended to leave the normal collar on but have an extra strap attached to it with velcroI make all my own collars and the holes are much closer than the norm
but I would still like an extra security
Sam