Loki is 12 pounds and he has the small size. The size is fine, there was just lots of extra webbing after it was adjusted so I cut it off and melted the edge of the webbing with a candle to stop it from fraying.
It *does* help with barking and such because the wrap around the muzzle is kind of like a calming signal for dogs. It works for Loki in stressful situations and I've seen it work on crazy big dogs who suddenly behave when their GL is on. It doesn't solve the problem, but it does help. If your dog doesn't have any anxiety issues I would recommend the Easy Walk harness instead.
Here's the thing, if you are just teaching walking on a leash then you don't have to use it forever. If your dog can't deal with having it on (constant pawing, etc.) then try the Easy Walk harness. Either way, you have to teach them to stop pulling but these tools make it easier. I still use Loki's Easy Walk because I like how it fits him. I only use his GL in stressful situations which we try to avoid anyway, but it's still nice to have.
If you have no idea what these things are I have pictures on my website. I have some GL's (just in size small) and all sizes of easy walk harness. The petite is TINY, like too small for Sammy who is barely 6 lbs. So that's why we have the in-between sizes.
Hope that helps! Let me know if anyone has any questions. I've used these on my dogs and on other people's dogs in training classes and on unruly neighbor dogs
