Let me start off by saying that I have been involved in aquatics (safety oriented) for about 6 years. So with that finding a lifejacket that fits is key to safety. First you definently want one that is US Coastguard approved (they will have a stamp/lable inside then. Second look for the one that fits his size by weight and height (not all of them have hight measurements). Third the jacket should have the adjustable straps that buckle in front and one that goes between the legs. I also agree with the responder that said when the jacket is on the child it should not come up past his chin. Nor should it go down past their waist. It needs to be snug enough that he can move, but the jacket is going to stay put. DO NOT buy one that is too big. That is why I highly recomend one with adjustable straps, so you can fit it to him and there is some room for growing and such. Lastly, shop around because you can spend too much on one, but don't rush and buy the cheepest one either. Hope this helps you or anyone reading your responses. If you have any other questions just let me know, I am more than willing to help.