This is a regular quick release buckle. On a good quality collar, it
shouldn't come open of the dog hits the end of the leash. Now, on a cheap dollar store collar, all bets are off... I did have one that was given to me that I tossed after the second time it popped open (thankfully NOT with this dog). On the other hand, a safety buckle is designed to pop open when X amount of force is applied to it, and unless if has a safety feature of some sort to prevent that, shouldn't be used as a walking collar.
2013-2-28 Dogs 044 by
Rosemary Elwell, on Flickr
Here, she is wearing a martingale along with her custom Cali Girl collar (absolutely loved that collar, butter soft from day one, and held up beautifully... this picture is after nearly five years of 24/7 wear). Properly adjusted, a martingale in pretty much escape proof.
2017-6-12 Ilka DSC_0645 #2 by
Rosemary Elwell, on Flickr
I very rarely every use a regular buckle collar of any type for walking, because of the concern about them slipping it off and getting lost. Most of our walking is done in a martingale.