I originally got this for dog to wear to the zoo on a hot day. I wasn't expecting a lot. He is black so I figured that even just wearing something light would make a difference. But the effectiveness of this vest was unexpected and brilliant. He wore it at the zoo and it extended his interest and energy significantly. Since then it has become a staple for us. This vest made walking in the Oklahoma 'feels like 113º' days possible. He rolls and plays in it, but it has stayed together. When he gets dirty it's so easy to just throw it in the washing machine. The large is the perfect size for him—he's about 100 lbs. If you want your dog to be more comfortable this summer, then this is a must buy!