The Ofuton Warm Adapter in an insulating inner sleeping bag designed to be used with the Ofuton System products for enhanced warmth and comfort. Made from a polyester fleece material, the Ofuton Warm Adapter offers improved heat retention while also keeping your mat and comforter clean, and is machine washable for easy care in between uses. Four connection points on each side allow the Warm Adapter to seamlessly integrate with the System Ofuton products.