Ether Light XR is the thickest and warmest sleeping mat in the Ultra Light range, due to using new insulation, Thermal Core®. The Air Sprung Cells still provide four inches of stability and comfort, while Thermal Core® insulation prevents convective heat loss and internal air movement. This results in true four-season performance perfect for backpacking, light weight camping, bikepacking and sea kayaking. Best Use: Light Weight Cold Weather Backpacking Comes With: Stuff sack w/ integrated pump, repair kit & Pillow Lock Fabric: Durable 30D/40D nylon R-Value: 4.1 Season Rating: 4 Season Special: Anti-microbial liquid-extruded TPU lamination to reduce delamination Thickness: 4 in / 10 cm Small: 168 x 55cm Packed Size 20.5 x 11cm Packed Weight 500g Regular Rec: 183 x 55cm Packed Size 20.5 x 11cm Packed Weight 525g Reg Wide: 183 x 64cm Packed Size 24 x 12cm Packed Weight 665g Large: 198 x 64cm Packed Size 24 x 11.5cm Packed Weight 665g Rec. Large: 198 x 64cm Packed Size 23.5 x 12cm Packed Weight 725g Stuff/ Pump Sack Weight 55g