I purchased 2 of these for my Standard Poodles (24" and 25" -- 50-55 lbs) in a size 56. They fit very well and are extremely warm. I might have been able to get by with one size smaller, but they wear them at night and I like the extra roominess so that nothing binds when they curl up. They are easy to put on and take off and there is no static electricity. The attention to detail is striking -- it completely covers the back and hind legs but there's a nice cut out for the tail. They can take care of business with no mishaps. And as a bonus, it's extremely good looking.