Chain Martingale collars are excellent for dogs that can escape their collars, or need an audible correction. These are the collars I personally use with my dogs.
These collars should only ever be used when there is a leash attached to one end and a hand attached to that leash. These are constricting collars that can cause harm if not used properly and with common sense.
They feature some of the strongest buckles on the market today using YKK and Duraflex. I use welded metal hardware that is proven to last years without breaking. My slides (or size adjusters) are some of the most durable out there. Plain webbing items are made with duraflex plastic slides and ribbon on webbing are made with metal slides.
All items are assembled on my 1541 Industrial sewing machine with triple bonded Nylon sunguard thread that is nearly impossible to break by hand.