What Our Gearhead(R) Experts Are Saying:"I'm a chronic side sleeper and the Riff lets me tuck a knee without cold spots. It's warm, packs small, and the Endless Promise build feels future-minded."We turn cold nights into cozy ones with the Riff Endless Promise Sleeping Bag: 15F. The signature spoon-shape opens room at the knees and elbows so we can shift naturally, while targeted baffling and draft control help hold heat when temps dip. Built within the Endless Promise program, the materials and construction are chosen for long life and a clear path at end of life-adventure-ready today and tomorrow.