No the Gentle Leader is something different. The easy walk is just a harness that goes around the belly and attaches in front near the breastbone. This counters the dog pulling, but I like it because the leash doesn't attach to the dog's back, which I find akward (and so does Loki.) When you walk them it's almost like the leash is attached to the collar but no pressure is on their neck.
This is the easy walk:
http://www.premier.com/pages.cfm?id=74
I'm not sure how she could get out of if it's adjusted properly. Unless she could somehow get her paws up through the front, but if it's adjusted right there won't be any extra space to do that.
Here's the link to the martingale collar - it's in the middle of the page:
http://www.premier.com/pages.cfm?id=13 The Premier® Collar - A martingale-style collar which offers greater control without the danger of choking. Its escape-proof design reduces coat damage and can easily be adjusted as your pet grows. Available in 25 colors (cranberry, red, pastel pink, hot pink, dusty rose, burgundy, deep purple, bright purple, lilac, ice blue, cadet blue, royal blue, navy, teal, green, electric lime, neon lemon, gold, blaze orange, fawn, brown, black, charcoal, silver and white. Color Chart
Hope that helps.