This is my first heated garment, and I'm glad I went with a base layer vest. This works really well on its own, or I can easily throw a jacket or parka on top of it without too much extra bulk. It comes with an included battery pack, which not all do, so that's a benefit. On most walks in below 30* weather I've had to turn it off because it works so well. I've used it on 5 walks so far, and have not needed to charge the battery pack yet. That's a total of aprox. 5 hours.See full review