We love these. We bought the medium for our 38lb golden mix, large for our 63lb dane/boxer mix, and the XL for our 88lb monster collie.
Literally THE only downside we've found is that the neck strap tends to loosen with use and I have to tighten it again before the next use to ensure it fits snug around their chests and doesn't slip down their back. That's why I docked 1 star. The support cushion for the front of the neck also always flips around on my dane mix so it's facing outwards, but it doesn't seem to really affect anything so who cares.
The dane mix got in unexpectedly early into our pool days without her life jacket and sank to the bottom immediately like she was wearing concrete shoes. We were in the pool next to her so her head was only underwater for a second. We immediately picked up life jackets for everyone after that incident. She's still a little nervous about going in where she can't touch, but she has come in with her life jacket on and it has kept her 100% above water.
The collie is an experienced swimmer and this just gave her a little extra support so she wouldn't get tired as quickly.
The golden mix has swam only a little and was pretty bad at it and nervous about doing it, but this gave him the confidence to swim and he's improved leaps and bounds!
The handles are great and we've used them a fair bit to help give the dogs a boost in and out of the pool and in & out of the doggy pool boats we bought them. No complaints there. We've been using them all summer and they show zero signs of wear. The buckles are easy and it's easy to get them in/out of their jackets. We wrote their names on the front handle so it's easy for us to determine which belongs to which dog. We usually dry them out after use by strapping them into our deck railing for a few hours before going into our deck box for storage. They fit well, they're very adjustable, and I would buy them again if I needed more!