Love this liner…bought for my whole family & all are happy with them.I ordered for my Dad who wears a US men’s small. He couldn’t even zip it. I returned it and ordered a medium. He could zip it but it was too snug to function in. I gave it to a friend who wears a women’s small. Fit her perfectly. I reordered a Large size for my Dad and it fit fine. The vest is not much to look at, so would need to be worn under something. But the heated areas is what I was after. Lumbar, between the shoulder blades and two in front. The battery is easy to charge and attach in the pocket. And there is info on the packaging about how to order more batteries. I like the product. It just runs very small.Great value, except for access to temo control.Works well, I wish it had a bottom draw cord to keep the heating element on my back better and I wish I could use a different a battery. But that said, it works well and goes unnoticed under my clothesLoved the vest, just needed a larger size. Will be comfortable for his motorcycle ride. Vest reminds me of a fishing vest, he can put it on over his shirt and his larger coat on as well if needed. Can't rate comfort nor battery life yet.So far works well. I use this while riding my motorcycle here in NJ. Kept me warm in low 40’s with my leather jacket and liner over this vest. Wore a t shirt under this vest and kept the vest at low for an hour long ride. Was totally comfortable the whole ride. I’m 5’8” 157 lbs. 40” chest 30” waist. Medium fits perfect. Highly recommend so far.Generally in north west PA the weather in January would be a good test for the heated vest. So far the winter has been mild and I only used it once and it was on the low setting. But I can tell you I was very comfortable when the temp was around 30, with no wind.I bought this for my wife because she hates the winter chill. It's super thin so she could easily wear it under her sweater and stay toasty warm while we were out looking at Christmas lights. It's a very thin and light garment which makes it great. I plan to use it in the fall/winter to keep myself warm on long motorcycle rides. Can't comment on the battery life as it's only been used a few times but each time it was used for 3-4 hours and performed flawlessly.This is a great product. Well constructed, evenly heats and I love the variable settings. Definitely worth the investment.