Size & Suitable temperature: The overall size of this sleeping bag measures 180cm long and 75cm wide, the hood is 30cm long. The recommended temperature rating is from 5C to 20C (depends on the surrounding environment and personal circumstances). Loop and hoop fastener: The extra loop and hoop fastener helps keep the zipper in place and prevents heat from escaping from the top of the zipper as well. Multifunctional zipper: The envelope sleeping bag has a zipper down two sides, running the length and the width of the bag. You can either unzip your bag for ventilation if you are feeling too warm or completely unzip your sleeping bag and use it as a large blanket. Any position: In an envelope sleeping bag, you can sleep in almost any position you like. A rectangular bag offers more freedom of movement and a variety of sleeping positions. Popular choice: Rectangular sleeping bags are a popular choice for car campers. You can bring a rectangular sleeping bag into the campground, and this one is a warm and roomy option for families and car campers.