Photo courtesy Cascade Designs.
Alan Dixon reviewed the Therm-a-Rest ProLite 3 back in 2004, when he noted that ‘Cascade Designs has whacked more than a quarter pound off their lightest sleeping pad.’ The weight for the Small or 3/4 length mat had been reduced to 370 g (13 oz) at that stage. Well, they have reduced the weight even further: the Small (3/4) is now down to 310 g (11 oz). This is getting rather light.
In the process the claimed R-value has dropped a bit, from 2.3 down to 2.2, while the thickness has stayed the same at a nominal 25 mm (1 in). The R-value is going to vary a bit depending on what pressure you put into the mat. This is discussed further under ‘R-value.’ The nominal length and width dimensions have stayed the same at 505 x 1200 mm (20 x 47 in), ignoring the welded edges. Note however that the mat tapers at the bottom end, down to about 380 mm (15 in).
The foam inside is urethane – as usual with any decent air mat, and the fabric is nylon top and bottom. Both top and bottom surfaces are covered in lots of little dots of something (maybe polyurethane again). The web site says ‘Rest Comfortably: Bottom grips and textured top surface hold the mattress in place while you sleep.’ This apparently refers to the little dots, but see below for further comment on this.
Camp below Matte, Via Alpina, Switzerland.
The foam has had star-shaped holes die-cut out of it to reduce the weight. These holes are visible when the mat is inflated, as you can see here. It is interesting to see that Cascade Designs have chosen the more expensive path of only selectively cutting these holes across the mat. That is, rather than taking a long slab of foam and feeding it through some sort of mass-hole-punching system, they have only cut the holes in the middle of the mat. They have left an unpunched edge down each side and across the bottom and a larger unpunched area at the top end where your head goes. You can see the unpunched edges here too. These unpunched areas are meant to provide extra support at the edges and under your head.
As a background to this I should explain that my wife and I have in the past each used a 3/4 length Therm-a-Rest Deluxe LE mat, which has a very nice soft fabric surface and is about 50 mm (2 in) thick. These have been faithful companions for many years and on many ski-touring trips. Sadly, they are no longer made. The only trouble with them was the weight – 750 gm (26 oz). Some of that high weight was due to the coring used: longitudinal holes. That design did however make the mats quite warm in the snow.
Camp at the foot of Glacier de Moiry, Chamonix to Zermatt, Switzerland.
We wanted to reduce our pack weights some more and reluctantly accepted that we needed lighter air mats. The weight of the new ProLite mats was good, but would they be warm enough and soft enough? We took the plunge, got the mats, and set off to Switzerland for another two months walking. The verdict was that they were fine.
I had better qualify that verdict. The mats were normally used on alpine snow grass, as shown here. This can be fairly soft in itself, and does provide some insulation from the ground. Mind you, the water in that tarn was cold!
How are they inflated? Like all good foam-filled air mats, you unroll the mat and open the valve. Go away for a few minutes, and they will self-inflate – up to a point. Typically my wife looks after this while I am looking after the tent: when they seem to have reached equilibrium she gives them about three large puffs and does up the valve. I imagine that over time the puffs might put some moisture into the mats, but we haven’t noticed any problems. We always store the mats on their sides inside the house with the valves open when not in use, and I think (hope) that they dry out a bit during storage.
Evening at Mumbedah Creek, Kanangra-Boyd NP, Australia.
While my wife likes her mat fairly firm, I often let a tiny bit of air out of mine. Doing so lets my hip get closer to the ground, but if I am not sleeping on snow that doesn’t worry me. But the slight reduction in pressure does significantly increase my perception of comfort.
We normally tie our two mats together so we don’t get a gap in between. This is good for those cold nights when we supplement the warmth of our UL quilts by snuggling up together. (Hiking with your wife has some advantages!) The photo here shows one of the blue tie straps just to the right of my wife – it was a mid-summer warm evening. However, while this works excellently with the parallel-sided Deluxe LE mats, it is a bit more tricky with the tapered ProLite mats. The end result is that the foot end of the mats are close together but the foot end is narrower. Well, true, but the narrowness is not a real problem, given the significant weight-reduction.
I had better also add that these are only 3/4 length. I cover the rest of our tent floor with some 5 mm EVA-30 foam. That protects the silnylon floor of the tent and provides just a bit of insulation under my feet. The combination is generally enough, even at some altitude in our Alps as shown below – dawn at 2,100 m (6,900 ft), North Rams Head, Kosciusko NP, Australia. Of course, if we have spare dry clothing available I often fold that up and put it under our feet as well.
Dawn at North Rams Head, 2,100 m, Kosciusko NP, Australia.
We met a significant problem in the field with the way the mats slide around on the silnylon floor of our blue tent. My impression is that the PU dots are really good at sliding on the silnylon, and discussion with my contact at Cascade Designs more or less confirmed this.
I spoke with Doug Jacot, our Therm-a-Rest director. He said that the problem is the Sil-nylon groundsheet. Even the NeoAir, which has one of the best non-slip treatments, can slip on a silicone-treated floor. As you mentioned, adding the silicone sealant stripes to the floor of the tent really is the best option, other than to use a tent without a silicone-treated groundsheet.
Well, as expected, but I have to say that suggesting I change my tent was hardly useful! And I had already added silicone stripes to the floor of my tent, but they seemed to have very little effect on the sliding. I do wonder whether the dots are there not to stop sliding but to prevent abrasion of the fabric surface. The dots are small, but they are packed really close together, and they do slide well.
ProLite 3 mat with silicone stripes added.
What the company did not suggest was putting the silicone stripes on the underside of the mat. So I tried this with Permatex Flowable Windscreen Sealant 65AR. You can see the stripes in the photo here. I want to emphasise that these stripes of silicone are really thin: I ran a very thin bead along, then smeared it out with my finger carefully. There are no lumps, and the weight gain would be in the order of maybe 2 – 3 grams. Making the stripes any thicker would not improve their grip. After a rather serious trip in Wollemi NP (a long story…) I can confirm that these stripes made a huge difference: the mat did not slide around. It may be that the silicone stripes on the mat did grip against the silicone stripes on the groundsheet: you may need both. With all due respect to Cascade Designs, I have to ask why they can’t do the same thing?
We all know that some companies make exaggerated claims for the insulation value of their clothing, sleeping gear, and mats. We mentioned above that the claimed R-value for the ProLite is 2.2, but obviously this should be measured. Using our insulation test system we measured the ProLite mat with the bottom surface cold and the top surface hot – the way you would use the mat in the field.
ProLite mat R-value.
Making the measurement takes time, as mats are good insulators and the heat flow is slow to stabilise. There is always a transient at the start which purely an artifact of how insulation testing works, so we have to ignore that. The plot here shows the R-value at several different thicknesses, from fully inflated (and lightly loaded) to under-inflated and heavily loaded.
You should note that this test started with the mat inflated with a few breaths on top of its normal self-inflation, and this does not completely reflect field use. In the field your hips and your shoulders will depress the mat locally, reducing the R-value right under them. Also, you may not blow the mat up fully as that tends to make it rather hard. When the mat is under-inflated just a little bit you get more of it supporting you, which is more comfortable, although this means some bits of you may be a bit cooler than other bits. That’s normal.
My assessment is that the claimed R-value of 2.2 is fairly honest, although if you go for ‘comfort,’ bits of you will see a slightly lower R-value.
Do we like these mats? For non-snow use, we do. We haven’t tried them in the snow, and probably won’t. Even though they are thinner (at 25 mm or 1 in) they seem to be quite comfortable, and at 310 g (11 oz) they are much lighter. With a quoted R-value of 2.2 and a measured consistent with that, they have less insulation than our Deluxe LEs (about 6.7) which we use in the winter on snow, but they seem fine for three-season use.
|Model||ProLite, Small (3/4 length)|
|Size (measured)||Small: 505 x 1200 mm (20 x 47 in)|
|Thickness||25 mm (1 in) – approx, depending on inflation|
|R-value||Claimed 2.2, measured 2.5|
|Weight (quoted)||310 g (11 oz) for Small|
|Weight (measured)||315 g (11.1 oz) for Small|
|MSRP||US$80 for Small|
|Other sizes||Extra Small: 510 x 910 mm (20 x 36 in), 230 g (8 oz), US$60
Regular: 510 x 1830 mm (20 x 72 in), 460 g (16 oz), US$100
Large: 630 x 1960 mm (25 x 77 in), 630 g (22 oz), US$120
- Light weight
- Self inflating
- Seem tough enough
What’s Not So Good
- They slide around on silnylon!
Disclosure: The manufacturer provided this product to the author and/or Backpacking Light at no charge, and it is owned by the author/BPL. The author/Backpacking Light has no obligation to review this product to the manufacturer under the terms of this agreement.