Size and Suitable Temperature: The total size of this sleeping bag is 180 cm long and 75 cm wide, the hood is 30 cm long. The recommended temperature range is from 5°C to 20°C (depending on environment and personal circumstances). Velcro: The extra Velcro helps keep the zipper in place and prevents heat from escaping from the top of the zipper. Multifunctional Zipper: The envelope bag has a double-sided zipper that runs along the length and width of the bag. You can either open the zipper for ventilation if you feel too warm, or open the sleeping bag completely and use it as a large blanket. All Positions: In an envelope bag, you can sleep in almost any position you want. A rectangular bag provides more freedom of movement and a variety of sleeping positions. Popular Choice: Rectangular sleeping bags are a popular choice for car campers. You can take a rectangular sleeping bag to the campsite, and this one is a warm and spacious option for families and car campers.