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 you’re 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 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.