I guess I am the oddball on collars here.  After looking at leather straps,
nylon straps, and collars with skimply elastic loops in one small section, I
chose for my two ferrets collars that are nylon with elastic inside the full
length of the nylon woven mesh.  I found them at the Super WalMart.  Because
they were originally 8" long, I cut down and the end melted to stop fraying.
Being made of woven nylon, the hasp can go in anywhere, allowing for a
comfortable, custom, and secure fit.
 
I chose this fully elastic collar because I wanted to make sure that if they
get hung up on something, they can pull out without much problem before they
hurt themselves.  After the first 5 minutes of a St.  Vitus Dance protest,
each ferret gave up trying to take off their collar and now it is not a
concern by either ferret.  My experience is that a collar comes off of one
of them about once a week, usually because the name tag got hung up in the
track of the glass shower stall sliding door on the bathtub.  That's good to
me because then I know it is slipping off like it should, otherwise I'd find
myself with hung ferrets.
 
Its very simple to put the collar back on a squirming ferret as it doesn't
have to be unbuckled, just stretched out and quickly placed over the moving
head.
 
Each collar has a small jingle bell and a really great name tag system I
picked up at PetsMart.  Its a small metal cannister with a screw on lid.
Inside is a slip of paper with all of the info you want someone to have who
may find a lost ferret.  I've never seen one come open on its own.
 
The bell and tag are right on the D ring in the collar and jingle loud
enough to let somone know where each ferret is at any time, especially when
opening a door to a ferret-forbidden room (from either side).
[Posted in FML issue 1884]