At a glance Plusses: Lightweight, comfortable. Minusses: Slippery, moisture build-up inside.Weight: 250g Features: This is the lightest air mattress available. It’s a simple product with just a handful of features. It uses Therm-A-Rest’s triangular core matrix insulating technology – two stacked layers of triangular baffles that help create a stable surface and limit heat loss – and it has a single inflation/deflation valve and comes with an R-value of 2.0. Weight: Is it really 250g? When it’s inflated, it’s hard to tell because it feels like it weighs nothing and practically floats in the air when it’s manoeuvred around the tent. It’s 100g lighter than Therm-A-Rest’s NeoAir XLite – the previous lightest air mattress in the company’s stable. But unlike the XLite, the UberLite doesn’t come with a ThermaCapture lining to reflect radiant body heat, so the most obvious compromise here is with the low 2.0 R-value – it’s definitely a summer mattress. The fabrics used are also a very light 15D with a ripstop on the top. Comfort: The mattress inflates to 6.4cm thick providing plenty of padding from the ground. I camped on hard-baked ground and initially fully inflated the mattress, but this proved too firm and every time I changed position, the mattress squeaked noisily. Deflating the mat from its firmest position proved more comfortable and even when I lay on my side, my shoulders and hips did not touch the ground. In use: The mattress packs down so small and weighs so little, you barely feel its addition to your pack. Rolled up, it’s slightly bigger than a can of soda and weighs much less. It’s not a self-inflating mat and takes a reasonable effort of about 25 puffs to fully-inflate. I found it most comfortable at around 20 puffs – over-inflation makes the mattress noisier and creates a firmer and more slippery surface. Even under-inflated, I had trouble staying on during the night and the mattress itself tended to slide around the tent easily – no doubt due to its lightness. A sleeping bag with mattress loops would make a better combination. After inflating the mattress a few times, I noticed water droplets – from the moisture in my breath – had formed on the inside. This is common for all breath-inflated mattresses, but normally you can’t see the moisture – the UberLite’s fabrics are so light they border on transparent when held up to the light. Moisture can lead to mould, so careful storage will be important. Value: For the limited seasonal-use of this mattress, it is expensive. But for those who value their knees, it is a considerably easier and nicer mattress to carry than anything else out there. Verdict: A revolution in lightweight sleeping mats, the UberLite is comfortable and supportive. If shaving excess grams from your summer tramps is important, it’s worth a look.