Big Agnes Sidewinder SL 20 Degree Women's Mummy Sleeping Bag - 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’.