I’ve had friends buy a couple of these products before, and from what I’ve heard (and seen), this product is absolutely amazing! My friends and I are HUGE hiking fans, but we always have to bring along a backpack for first aid kits, snacks, etc. We start early when it’s cool out, and than normally try to reach the top around noon. The best thing about this is that whenever we are cold, we can just put the jacket on and than we are warm. But I’d we get too warm, we can just take off one of the sweatshirts and boom, just like that we have a fully functioning bag. It’s great and I would highly recommend this to ANYONE that does anything physical. It’s a must!