Review on Ultimate Trail Running Hydration Vest: TRIWONDER Backpack for Marathon - Stay Hydrated on the Go! by Bobby Montoya

I'm small but I took a medium/large and sewed it onto the back (took several hours on a sewing machine). The material is light and very beautiful when I put it on myself. He didn't jump at all during my long run with water, phone and snacks in my pockets. I like it better when the water is held in the front than when running when the camel holds the water in the back. I would not advise a small person to order a medium size unless you have the time/tools to sew them on.