To be honest, I didn't read all of these responses because I'm just taking a short break from my studies but I thought I'd throw in my own two cents.
I was first introduced to martingale collars as a kid because we adopted and fostered greyhounds. They were used mostly for greyhounds/sight hounds and are thus sometimes called a "greyhound collar." I'm pretty sure that is isn't until recently that they've started being used with all breeds.
I have noticed that you have to be careful with martingales because there are some brands/companies that market them as "humane choke" collars. These are often still built with some metal chain parts to them, but the chain does not go all the way around the neck, just the martingale loop. From what I understand, though I have never used one of these chain ones, is that there is no stop mechanism to them and they function much like a regular choke collar.
A true martingale collar, when fitted correctly, will stop constricting at about the two-finger point in between the two sides of the collar. A little hard to explain, but I'll soon post a link that will illustrate it better. Essentially, the dog cannot back out or slip out of the collar because it is too narrow for it to fit its head through, but also won't choke the dog.
I love them and use them for my German Shorthaired Pointer (and most likely other future dogs!). I recently found ones that have buckles! I LOVED this because in the event that my dog got caught on something, like a fence, he would never stop struggling to free himself in order for me to help him, it's against natural instincts! With the buckle, I could release the collar and help him.
Here's the link: http://www.trendyhounds.com/martingale. ... Martingale
. I recommend AT LEAST 1.5 inches width (depending on the size of the dog of course) because the greater surface area will result in less pain or damage in the event that the collar is too tight. I have a 1.5 inch on my dog and it's great!
[img][IMG]http://i874.photobucket.com/albums/ab30 ... 698e9f.jpg[/img]