The Bottom Line
(4.5 / 5)
The Ultrasphere 4.5 sleeping mat from Rab is surely one of the greatest sleeping mats out there. It’s not cheap, but it is extremely warm, packs tiny and, at 370 grams, you’ll hardly notice it’s there at all.
Purchasing
The Ultrasphere 4.5 is available direct from Rab, but also from numerous other retailers – Taunton Leisure usually has it at a good price. The list price for the Regular version is £170, but discounts are often available so expect to pay around the £150 mark. The Wide and Long versions go for about £10 more, depending on the retailer.
In Use
The mat is very comfortable to sleep on and, as expected, extremely warm. The Regular version is also surprisingly generous: I am 6’2″ and use the Regular. I probably could have benefited from the Long version, but I didn’t want the weight – and the Regular is more than good enough! However, my two complaints about the mat are both in its use. One is the valve: it is not a standard size, being smaller than most I have seen, and can be quite difficult to open and close. It also makes attaching and detaching the pump sack harder than it needs to be.
While it’s not unique to this mat, the second issue is how slippery it is. Unless I’m on dead-level ground, I’ll often wake up at the other end of my shelter (I use the Vango Nevis or a DD 3×3 Tarp), which can be annoying if I’m sharing the shelter with someone else.
Technology
The Ultrasphere uses Rab’s patented TILT insulation technology, instead of traditional down insulation. In plain English, this means that it has two layers of metal foil inside it, to reflect radiated heat back to your body. The position of the foil and baffles also cut down on air convection in the mat, so heat loss is minimal (hence the high R-value of 4.5). This has two consequences:
- The mat is extremely light and packs down small, while retaining warmth.
- It makes odd crinkly noises when you fold it up! (It’s no louder than any other mat when inflated though).
In the Bag
The Ultrasphere 4.5 comes with its own pump sack – unlike some pump sacks, it is not a drybag. However, it’s so thin and light that it rolls up with the rest of the mat. While it is slightly inconvenient that it doesn’t have the multi-purpose perks of being a drybag, I do still find it useful to store my things neatly in my tent overnight.
The rolled-up mat is impressively small and, unlike some products, it is actually relatively easy to roll it back into the bag it came from. Make sure to get as much air out as possible, then fold the mat in four along its length before rolling towards the valve end (with the valve open).
If you’re looking for an ultralight sleeping mat on more of a budget, you might consider the Trekology UL80 for summer camps only – or the Salewa Mat Lite, if you want something high-quality (and about half the price of the Rab). You might also be interested in sleeping bags: for UK 3-season use, I use the Alpkit Pipedream 400 – or in summer, the Mountain Warehouse Traveller 50, which is only £20.