I have used a heater body suit and for really cold weather, I'm talking well below zero with winds 25mph or more I have found it the only way I could stay warm. I've tried all the bulky layers of different clothing and eventually it got to the point where it was too bulky to shoot and still not very warm. Now when hunting in the cold I use my heater body suit and the same clothes I use for temps around 30 deg on underneath and stay reasonably warm. It's basically a sleeping bag with legs and no arms, it has a very quiet and easy working zipper down the middle so you can easily open up and slip upper body out for a shot. Works for both rifle and archery hunting for me. Hope this helps.