The generously sized Sea to Summit Basecamp Bt3 Sleeping Bag features THERMOLITE which may be the best choice when affordability is a primary concern, and when easy care is an issue %u2013 for instance - for camping in desert or sandy riverbank environments. The spacious, flexible Basecamp Bt3 is insulated with high quality THERMOLITE fiber, built in to the bags using a unique WAVE LOFT construction. The inner fabric %u2013 an artificial %u2018silk%u2019 made of polyester %u2013 has to be experienced to be believed. The Bt3 has an EN rating of 18F/-8C (lower limit) The Basecamp Bt3 has been designed to work with Sea to Summit sleeping mats and Aeros pillows to create a truly comprehensive sleep system. Slide your mat into the small pocket at the foot of the bag and then use the strap and loop set-up to secure the upper section. Then inflate your Aeros Pillow to the perfect pressure before securing it into place with the elastic strap. Features: Use