Hi, I am 5'3" and wear a size 8-petite. According to the size chart, a Medium would fit best. It was way, Way, WAY too small. I tried it on over a t-shirt and had the side-zips undone. Now I have to accept that some thinks I should wear a size Large!Seems like a good product. Ordered the largest they had. It Did not fit.I kept it for someone smaller and ordered from a different manufacturer.I found turning on the vest was difficult to use and the instructions were not very clear.I live in the Midwest, and my child plays club and HS sports that start games outside in the second half of March and a Fall season running through early November… rain or shine (just no lightning). There are days when there aren’t enough down parkas, hats, scarves, gloves, and wool socks to keep the bitter wind out and the cold at bay. I wish I bought this years ago!! Easy to see how much life is left in the battery and easy to recharge it.This vest holds a charge well and keeps me warm skiing. On wicked cold days I am toasty warm and the last person on the slopes.The vest worked well for one winter. But now when I tried to use it again this year, with the battery fully charged, the "button" light only flickers and the vest won't heat. I tried switching to another (fully charged) battery. But no luck; the issue appears to be with the vest.I wish I would've got one sooner. I love this vest.