Specifically designed for those who sleep on their sides, the Sidewinder SL is engineered and ergonomically contoured to ensure warmth, comfort, and ease of use in any position you settle into. 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 sleeper's dream bag with technical features that roll seamlessly from one adventure to the next, and from one side to the other at night.