Ravean Heated Sleeping Bag Liner

The shape of a mummy sleeping bag, Ravean’s Heated Sleeping Bag Liner fits inside your current sleeping bag and keeps your core and feet toasty thanks to elements that wrap around each one. The heating zones can be individually controlled, cycling through three settings — high, medium, and low — to effectively increase the rating of your sleeping bag by about 20 degrees. They’re powered by one or two batteries that are stashed near your feet and can keep outputting heat for as long as 26 hours (with core and feet activated on low using two large batteries). Other features include a cinch on top to close it up tight to keep frigid air out, two-sided zippers for easy opening from either inside or out, and an alternate model that’s wearable thanks to a heated hood, sleeves for your arms, and a half zip.

Learn more at Kickstarter – $180+