Paws Aboard Doggy Life Jacket Size XXSmall (0-6 lbs) - Red New Without Tags.
Bought this for my mother in law, but it fit too snug on her dog.
Paws Aboard Dog Life Jacket Size guide:
XXS
Weight: 2 - 6 lbs.
Body Girth: 11 - 16 inches
Body Length: 6.5 inches
Neck Girth: 7 - 9 inches