Our use of a 75D Polyester makes for a tougher, more abrasion resistant base, while at 3.8cm thick, the Camp Mat S.I. Rectangular is comfortable enough to keep anyone from pushing through to the ground. The high 4.0 R-value also means its great to use in all year round.DeltaCore-VTechnologyRobust and durable 75D polyester with extrusion laminated TPU used on top and baseSmall vertical DeltaCoresin body contact areas (shoulders, hips and feet) keep you warmerLarger vertical DeltaCoresin non-body contact areas reduce the mats weight and bulk3.8cm thickMulti-functional, high flow-rate valveGenerously shaped rectangular sizeMat: 100% Polyester with TPU lamination; Valve 100% TPU; Insulation: 100% Polyurethane foam; Stuff Sack: 100% Polyester