I have a Doberman at 75 lbs. Bought the large. Perfect fit. I sleep in a hammock when we are backpacking He sleeps under me. I do need to pull the cover over him whenever he spins around at night to get comfy, but he and I don’t mind:-) He kept toasty warm at 45 degrees! It would be nice if it could be made lighter weight… but with dog nails and all, not sure if that is possible. However when it is cold out I am willing to take the weight for my pup. Awesome Product!