Specifically designed for those who sleep on their sides, the patent pending Sidewinder Series was engineered to ensure warmth, comfort, and ease of use no matter which side youre on. Constructed with features you expect from a traditional mummy bag with additional body mapped insulation to optimize warmth where you need it and minimize pressure points and other side effects. The Sidewinder SL is a side sleepers dream bag with technical features that roll seamlessly from one adventure to the next, and from one side to the other at night.