The durability of Ruffwear harnesses cannot be matched! I picked these harnesses as I was looking for something that would be comfortable to leave on our dogs overnight during a multi day camping/hiking trip. Our small dog is 20lb, but tall and lean. He wears an XS. Our Great Dane is about 120 and wears a L/XL, tightened up quite a bit. The adjustability of the harnesses is a little tedious, but creates a great fit, which it’s important since our Dane has a deep chest but lean frame. It’s much better than her previous multi-way harness. She actually enjoys it so much that when we bring it out, she sticks her head straight inside and is ready to go! This is something she taught herself within a week, and never did anything like this with her previous harness! I’d call it a win. :)