This is the Sea to Summit Trailhead ThII Synthetic Sleeping Bag 30F Features: Season rating: 2.5 season WaveLoft construction for improved air-trapping for maximum warmth Quality PFC-free DWR-treated nylon shell material helps repel external moisture Comfortable 20D nylon liner fabric Full-length YKKA(R) #5 main side zip extends through the foot box zip for increased ventilation and allows the bag to be used as a comforter Oversized draft tubes over the zippers to seal in warmth Includes 70D nylon compression sack If you are new to outdoor recreation, or you only camp occasionally, the Trailhead synthetic mummy sleeping bag is a great value option. However, that doesn&';t mean we&';ve cut corners on comfort and versatility. Like all Sea to Summit synthetic mummy sleeping bags, the Trailhead utilizes WaveLoft construction to allow the insulation to expand out into air-trapping curves for maximum warmth. As the temperature rises, the full-length zipper (which curves around through the foot box) allows you to sequentially increase ventilation to the point where the mummy sleeping bag can be opened flat and used as a quilt. The tapered-rectangular mummy cut of the Trailhead gives you plenty of room to move, regardless of your sleeping position.