"I have a 5.5 lbs female chihuahua that was spayed and sent home with the plastic e collar. It litterally terrified her. She wouldnt eat or move with it on. I went to the store and bought the black "comfy collar" but it was even worse, making her choke. I then tried cutting a baby onsie, but she walked right out of that. Finally we tried the pro collar and it is wonderful. She doesn't like getting it on, but once it is there it doesn't crush her ears, or restrict her vision. She is comfortable and happy, eating, and recovering. It would have been a MISERABLE two weeks with out this ring. She wore the size small. I highly recommend it for chihuahuas!"