Field Information:
Location(s) where test was conducted:
I have used the Therm-a-Rest ProLite 4 as my only sleeping pad for the last 18 months. It has been on numerous long weekend backpacking trips, Appalachian Trail sections hikes of five and eight days, and several multi-day car-camping trips. All told, I have slept on the ProLite 4 for about 35 nights since it was purchased.
These trips included both summer and winter trips, all in the Southeastern U.S.A.: Virginia, North and South Carolina, and Tennessee. Nighttime temperatures ranged from 75 F (24 C) in the summer trips, down to 15 F (-10 C) in the winter. I slept on the ProLite 4 in my hammock, inside a tent, under a tarp, and in A.T. shelters. Elevations ranged from sea level up to over 6000 ft (1830 m) in the Great Smoky Mountains.
Similar products used/owned:
I have used other Therm-a-Rest mattresses and various closed-cell foam pads during my backpacking career.
Description:
The Therm-a-Rest ProLite 4 is a self-inflating camping mattress, consisting of an open-cell foam core with a waterproof fabric cover. The pad can be inflated for use, and deflated for carrying. The ProLite 4 is part of the 'Fast and Light Series: Engineered for Extreme Adventure.' The Therm-a-Rest web site calls it
'the lightest, most compact 4-season mattress. Great for mountaineering, winter camping, backpacking, and multi-day adventures.'
My ProLite 4 is made from a very light, almost translucent orange fabric. The foam has a pattern of star-shaped holes in it, presumably to reduce weight.
The ProLite 4 is available in three men's sizes and one women's size. The men's small is 20 x 47 in (51 x 119 cm) and 16 oz (480 g) which might traditionally be called a 3/4 length pad. The men's regular is 20 x 72 in (51 x 183 cm) and 24 oz (680 g). The men's large is 25 x 77 in (63 x 196 cm) and 33 oz (930 g), and the women's specific pad is 20 x 66 in (51 x 168 cm) and 24 oz (680 g). The women's pad is slightly shorter than a men's regular, but has more insulation in the feet and torso. All of these mattresses in the ProLite 4 line are 1.5 in (3.8 cm) thick, though the men's pads have an R-value (insulation rating) of 3.2, and the women's pad has an R-value of 4.1. (I don't know enough to explain R-values, but the reader might get some idea of the relative warmth of these pads if I note that the popular RidgeRest closed-cell foam pad has an R-value of 2.6.)
The ProLite 4 didn't come with a stuff sack or a repair kit. The listed and actual weights are just the pad by itself.
In Use:
I can't say that I've had many 'extreme adventures' with my ProLite 4, but I have used it for all my backpacking trips for the last 18 months. In choosing a mattress pad for backpacking, I want to balance comfort, carry weight, and durability. In addition, I need a sleeping pad that will work as part of my pack frame.
Comfort:
I am a large guy -- 74 in (190 cm) and over 200 lb (97 kg), and I usually sleep on my side. I have used most every kind of closed-cell foam pad, and several different kinds of self-inflating pads, and I have found that I need at least 1.5 in (3.8 cm) of open-cell foam in order to get a good night's sleep. I have never had a comfortable night on a closed-cell foam pad except when sleeping in my hammock, where the pad is used only for insulation. The ProLite 4 is just thick enough for me to be comfortable on the hardest shelter floor, and I even slept on gravel one night and it gave me a good night's sleep!
The size Regular ProLite is 20 x 72 in (51 x 183 cm), which is plenty wide enough and long enough for me when I am sleeping on my side. It is not wide enough when I try to sleep on my back -- my shoulders and elbows fall off the sides of the pad, which is uncomfortable and annoying. I have used an older 25 in (63 cm) wide Therm-a-Rest, and it was wide enough for me to sleep comfortably on my back. If this were my normal sleeping position, I would want the size Large ProLite.
Therm-a-Rest sells the ProLite 4 as a four season sleeping pad. I have used the pad during the winter in the Southeast U.S.A., in conditions down to 15 F (-10 C), and it has been consistently warm both in a tent and on a shelter floor. I don't have any experience in severe winter conditions or on deep snow, but my understanding is that many serious winter backpackers use two pads for insulation anyway.
Weight:
At 24 oz (680 g), the ProLite 4 is heavier than a closed-cell foam pad, but lighter than other self-inflating pads of comparable thickness and dimensions. I know I could save almost a full pound (500 g) by carrying a lighter closed-cell foam pad, or an ultralight torso-length self-inflater. However, when I balance weight against the level of comfort, the ProLite 4 is the most comfortable pad for the weight that I have tried. As the Therm-a-Rest website says,
'shoot for a mattress that’s comfortable but within your goal for weight. Comfort and weight are trade-offs, as the thickest mattresses are often the heaviest.'
Durability:
The ProLite series of self-inflating pads is made of lighter and less-durable materials than other Therm-a-Rest pads -- their website even says that the pads
'are engineered for users who will be carrying their mattress, and consider mobility and packability slightly more important than durability and comfort.'
I have never used the mattress on bare ground or inside a shelter without some kind of ground sheet. In shelters or under a tarp, I normally use a lightweight, breathable sleeping bag cover which has a coated-nylon floor. The pad goes inside, with my sleeping bag on top. This protects the pad from splinters or sharp rocks, and keeps me from rolling off during the night. Inside my tarptent, the sil-nylon floor is normally the only thing between the pad and the ground.
The ProLite 4 has proven quite durable. I have never had a leak or a puncture the entire time I've owned this pad, but then I can say that about every self-inflating pad I've ever owned. Maybe I've just been lucky.
Carry and Use:
The ProLite 4 Regular rolls up into a fairly small package. I like to fold it in half lengthwise first, then roll it up. That way, it fits into a small stuff sack about 5 x 11 in (13 x 28 cm), which fits easily inside any of my packs. I have not had any trouble deflating the pad, though I have never been able to make it as small as it was when it came from the factory.
On some trips in the past two years I have used ultralight packs, which require a sleeping pad as part of the suspension system. With the Equinox Katahdin, almost any pad would fit inside the main compartment, and the ProLite 4 worked as well as any pad. However, my Six Moons Designs Starlite has a special pad pocket which forms a rigid suspension, and it requires that the sleeping pad be no wider than 20 in (51 cm), and not much thicker than a 3/4-length closed-cell foam pad. Folded in thirds, the deflated ProLite 4 fits easily inside the pad pocket, and provides a reasonable amount of support.
Using the ProLite 4, like any self-inflater, requires that I inflate the pad before I can go to bed. According to the manufacturer,
'When you open the valve, the open-celled foam responds by soaking up air, similar to a sponge absorbing liquid. Self-inflation is what makes Therm-a-Rest mattresses easy to use and comfortable. Once the mattress has inflated, you can adjust the firmness by adding or letting air out. It's that simple.'
In my experience, the ProLite 4 has never self-inflated like this -- I have always had to blow air into the mattress in order to inflate it. Once the mattress is fully-inflated, though, I have been able to adjust the comfort level by letting air out until I 'settle in' to just the right firmness. I have found that the mattress is more comfortable if it's not inflated all the way.
