The Salewa Diadem Extreme is an inflatable mat with an R value of 4, six centimetres thick, weighing 540 grams and packing to 12 by 24 centimetres. An R value of 4 is the figure that matters: it is enough for snow and shoulder season ground, which is exactly where a thin summer mat stops being enough.

• R value 4: insulation against the ground, adequate for cold ground and snow rather than summer only.
• 6 cm thick, 183 by 56 cm: deep enough that a side sleeper does not reach the ground through it.
• 540 g, packs to 12 by 24 cm: light and small for the warmth, which is what puts it in a mountaineering pack.
• Pump sack inflation: the stuff sack doubles as a pump, so you are not blowing warm damp breath into the mat. It is not a self inflating mat.
• Two way valve: separate inflate and deflate paths, so it goes flat in seconds.
• Fabric: 30 denier ripstop with an internal heat reflective layer and an anti slip base
• Field repair kit included
• 6 cm thick
• 183 by 56 cm