Personally i dont like collars they can be killers, a ferret who is left with a collar on unatended can risk climbing & getting the collar caught in something & maybe found dead, i dont like to see cats with collars on either for the same reason,
I dont walk my ferrets as there are far to many dogs around this place & obvioulsy they dont all behave well round ferrets i have seeen ferrets killed by dogs at shows , its a joint responsibility thing at the end of the day , just my opinion of course
Get them microchipped rather than use a collar & id tag