This muzzle is exactly what I was looking for. I provided the measurements as explained on the order page and received the a perfectly fitting muzzle for my German Shepherd Dog. The wide wire basket design allows for enough air to get to my dod so he can pant properly while running. This basket also allows him to open his mouth as wide as he likes to while running. I rollerblade my dog every morning and with this muzzle he gets the air he needs, can pant, doesn't need breaks and good air supply. It was the exactly what I needed and fits perfectly. I just ordered a 2nd one as backup. If your GSD needs a muzzle with enough airflow - this is it.