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-VTechnology Robust and durable 75D polyester with extrusion laminated TPU used on top and base Small vertical DeltaCoresin body contact areas (shoulders, hips and feet) keep you warmer Larger vertical DeltaCoresin non-body contact areas reduce the mats weight and bulk 3.8cm thick Multi-functional, high flow-rate valve Generously shaped rectangular size Mat: 100% Polyester with TPU lamination; Valve 100% TPU; Insulation: 100% Polyurethane foam; Stuff Sack: 100% Polyester