The Yate TREKKER is a time-tested and still very popular model that excels in material quality, workmanship and utility. The top material is Micro Brushed 75D polyester, which is resistant to damage and prevents the sleeping bag from slipping. The lightweight core reduces the weight of the product. WARM ZONE - under the back and the sides, the foam is lightened by horizontal channels and therefore there is more foam to ensure sufficient insulation.