Custom leather collars for Petsafe Stubborn Dog Fence Collars (Box style, exactly like in 1st picture and Exchangable button Battery style exactly like in 2nd picture)
 
Thru my own experience I discovered using nylon collars with the fence systems collars did not work very well. The collars would loosen themselves, the nylon would get smelly. So I handmade some plain leather ones with the holes for the fence collar. The leather collars weren’t loosening themselves and there easy to adjust. And the leather doesn’t seem to get smelly like nylon does and if they are getting dirty, cleaning with saddle soap is all I’ve needed to do. I've sold quite a few of these now and everyone loves them.
 
D Rings can be added if you want to use tags on the collar.

They can either be by the buckle like usual or farther down the collar. They can be 1 inch, the size of the collar or smaller (16 mm) to discourage anyone putting a leash on it.
 
The best way to measure for a dog collar is to measure off your dogs current collar. Measure from the middle of your buckle (where the leather or nylon folds over) to the MOST used hole on the collar. Or with a nylon collar measuring the total length of the current adjusted collar.