"I ordered a Fido Float life jacket for my 5 1/2 pound Chihuahua in size "Tiny", which is supposed to fit a 12-16" chest. My dog's chest measures 15" (with his sweater on), but the jacket was at least 2" too small to be able to zip it up. Even without the sweater, I couldn't get it zipped all the way up. So, I returned the life jacket to my nearest Petco store, and ordered an X-Small, which is on back order. This means that I had to forfeit the cost of shipping ($7.95), unfortunately. Hopefully, the larger jacket will arrive soon, and will fit. I don't think that I will order products online from Petco again."