Shoulder girth:  49.5" (126 cm)

Hip measurement:  34"  (86.5 cm)

Location:  Idaho Falls, Idaho
E-mail:  jmwlaw@ida.net

Examination: The ProLite 4 arrived in a small (6 1/4" x 11" x 4 1/4" or 16 x 28 x 11 cm) white box.  My initial inspection determined that the ProLite 4 arrived in undamaged condition. In addition to the information contained on the clear plastic bag in which the ProLite 4 was stored, there is a two-sided legal size page of instructions in English and three other languages (I think the other languages are French, German and Japanese).  The English version of the instructions were easy to read and follow.

The color scheme for the mattress is orange (top) and black (bottom).  The ProLite 4 looked exactly like what I had seen and read about on the Therm-A-Rest website.  I took the ProLite 4 to work and weighed it on our Neopost SE37 digital postal scale.  The ProLite 4 weighed in at 1 lb, 7.3 oz (660.5 g).  As such, Therm-A-Rest's advertised weight is fairly accurate.  The ProLite 4 has a tapered shape--similar to a mummy style sleeping bag.  I obtained the following measurements with a regular tape measure:  the length is 72 3/4" (185 cm); the width at the widest spot (near the shoulders) is 19 1/2" (49.5 cm); the width at the narrowest spot (near the feet) is 15 3/4" (40 cm); and the thickness is approximately 1 3/8" (3.5 cm).



Materials description:

As a general proposition, sleeping pads are supposed to (1) keep the user somewhat comfortable while sleeping on the cold, hard ground and (2) provide a layer of insulation between the user and the ground so as to reduce conductive heat loss.  Conductive heat loss is the transfer of heat through a solid material, i.e., heat from the user's body through the sleeping pad and into the ground.  Sleeping pads provide insulation generally by trapping and holding a layer of non-circulating air.  This "dead" air is held between the user's body and the cold ground.  Body heat gradually warms this layer of dead air providing an insulating barrier between the user's body and the ground.  The insulating ability of the pad depends upon how much air the pad holds and how free the air is to circulate.  Insulating ability is, in large part, a function of the types and quality of materials used in the pad.

My description of the ProLite 4 is based upon an inspection that did not include "taking the mattress apart" as I really didn't want to void the warranty and destroy my ability to use the pad comfortably during the rest of the test period.  The ProLite 4 is constructed with 13 oz (338 g) of "proprietary" die-cut urethane foam.  The top (orange in color) cover is made of polyurethane coated polyester.  The bottom (black in color) cover is made of nylon and features a "sticky-dot, non-slip" surface that Therm-A-Rest calls "super-grip" which is designed to keep the mattress from slipping on the sleeping surface.  The diamond shaped pattern that can be seen on both sides of the mattress is made by the air filled "die-cuts" in the foam.  See photograph above.  When properly inflated, the air actually pushes out on the covers creating a bumpy look to the mattress.  The die-cut foam apparently is designed to allow more air into the mattress.  When I pushed on one of the diamond shaped bumps, the air moved out of that particular "chamber" as the bump was depressed and would flow back into the "chamber" immediately after the pressure was released.  This tells me that after inflation, even though the air is able to flow to some degree within the mattress, it is unable to escape because of the air-tight covers surrounding the open-cell foam.  Thus, it appears to me that the ProLite 4 allows more trapped air into the mattress while restricting circulation of that air.  This should make for a warmer pad.

Therm-A-Rest claims that the ProLite 4 has an R-value of 3.2.  I'm not an expert in R-value but based upon the limited reading I've done, what follows is a very basic explanation of R-value.  Resistance value (commonly known as R-value) indicates the ability of a material to retard heat flow through the material.  The higher the R-value, the more effective the insulation.  For example, heat will flow through an R-8 wall twice as fast as an R-16 wall.  Different types of insulation have different R-values.  Fiberglass insulation usually has an R-value of 3 per inch (2.5 cm).  Dense packed cellulose insulation (treated, recycled paper) has an R-value of 3.8 per inch (2.5 cm).  In the 1970's, the Federal Trade Commission began to regulate claims regarding R-value by instituting "The R-Value Rule."  The rule is based on a mathematical term known to engineers as "The R-Factor."  R-factor is a measure of the ability of insulation material to resist heat transfer.  The R-factor is determined by placing carefully prepared test specimens between two plates in a laboratory apparatus and measuring heat flow through the material.  R-value is the R-factor of the material multiplied by the amount of the material.  For example, if a material has an R-factor of 3.8 and there are 3.5 inches (9 cm) of the material between the warm side and the cool side of the apparatus, the R-value of the material is 13.3.

Inflation:

For initial inflation, Therm-A-Rest recommends that the mattress be unrolled with the valve open, allowed to self-inflate, and then over inflated by blowing several breaths through the valve.  The mattress should be left in its over inflated state overnight.  For normal use, the mattress should be unrolled with the valve open and then allowed to self inflate.  The user can then adjust the pressure for comfort by releasing air through the valve or adding air by blowing air through the valve.  However, Therm-A-Rest cautions against using the mattress in freezing conditions if breath inflation has been used within several weeks prior to its intended use.  Moisture from breath which has accumulated inside the mattress may freeze damaging the mattress.  Therm-A-Rest also points out that under extremely cold conditions, the mattress will be slow to self inflate.  Under those conditions, since body heat will improve inflation, the mattress should be carried in the pack close to the body.  The mattress could also be wrapped around the body under the user's coat.

Deflation and Storage:

To deflate the mattress, simply open the valve, fold the mattress two to four times and sit on it to force out the air.  Close the valve and then roll the mattress from the foot end toward the valve.  During the rolling process the valve should be opened to let out the remaining air.  When rolling is complete, close the valve again and place the mattress in a stuff sack or place a wrap around it for traveling.  Therm-A-Rest recommends that the ProLite 4 be stored unrolled with the valve open and filled with air.  Apparently the mattress "remembers" the shape it holds most often and will self-inflate much faster if stored as recommended.  In the recommended storage state, the mattress could be stored under a bed, in a closet or behind a couch.

Repairs and Cleaning:

Therm-A-Rest suggests that the user purchase and carry a repair kit and follow the repair instructions that come with the kit.  To clean the mattress, inflate it completely with air and close the valve.  Wash the mattress in the bathtub using a soft bristle brush and any mild household cleaner or detergent.  Rinse the mattress well and leave it unrolled until completely dry.  The manufacturer warns that the mattress should not be stored if it is damp or wet as mildew will damage the covers and void the warranty.

Manufacturer's Tips for Use:

1	Check for objects under mattress that might be a puncture hazard.
2	Use a ground cloth or tent floor under the mattress.
3	Do not use mattress as a flotation device.
4	Do not expose mattress to flame or spark (the mattress contains non-flame retardant polyurethane foam).
5	Do not inflate mattress with high-pressure pumps.
6	Do not leave mattress inflated with valve closed in a car or tent on a hot day.
7	Do not contaminate mattress with DEET-based insect repellent, sunscreen or chlorine.
8	Do not expose mattress to long periods of direct sunlight (UV rays gradually destroy the coated fabric).
9	Keep mattress away from cats and dogs.

Initial Impressions:

Although I am somewhat concerned about the durability of the nylon/polyester outer-shells, the ProLite 4 otherwise appears to be well constructed.  Compared to my other full length self-inflating mattresses, the ProLite 4 is much lighter.  I really like having a full length, 1.5" (4 cm) thick pad under my aging bones--especially after a long day on the trail.  I also like the fact that the ProLite 4 is designed for use in colder weather.  The bottom cover on the ProLite 4 seems to "stick" to the different flooring in my home but none of those surfaces are as slick as a tarp or tent floor.  I have some concerns about the tapered shape of the mattress as well.  In light of the fact that I toss and turn at night, I wonder if I will be able to keep my body on the ProLite 4.

 

Field Testing Strategy:

Therm-A-Rest claims that the ProLite 4 is the "lightest, most compact 4-season mattress."  I intend to test those claims. In March the Scouts and I will be camping in the desert near Idaho Falls.  Since I was just released as the Scoutmaster after nearly seven years, I won't be hiking or camping with the Scouts every month as originally planned but I will go with them during the transition phase while the weather is still cold.  In addition, my family and I will be doing a 2-3 day backpack trip in both the Sawtooth Range and in the Jedediah Smith Wilderness area this summer.  I will try to get my girls out at least once a month.  Most all of these outings, will be in very mountainous terrain--5,500-8,500 foot (1,700-2,600 m) elevation.  Based upon the mattresses I have been using and am familiar with, I am already convinced that the ProLite 4 is one of the lightest full-length self-inflating mattresses on the market as claimed by Therm-A-Rest.  However, the exterior materials used to cover the ProLite 4 cause me some concern about its durability.  As such, I will be closely monitoring the wear and tear the mattress will experience on these outings.  I will purchase a Therm-A-Rest repair kit and report any repairs necessary.  Since I plan to use the ProLite 4 during the remaining winter months, I will also be testing the ease with which I can inflate the mattress in cold weather and how much the cold weather effects the ProLite 4's ability to self inflate.  I will also be testing the insulating qualities of the ProLite 4.

 

I will be testing the ProLite 4's ability to repel moisture, especially during our winter activities.  This will occur naturally as condensation from my shelter drips onto the ProLite 4 and as snow is unintentionally carried into the shelter on my boots and/or clothes.  I will also check on how quickly the ProLite 4 is able to dry in various temperatures.  On really cold nights, I will use the ProLite 4 on top of a closed cell foam pad.  During all of these outings I will be checking the ProLite 4 for comfort and fit as it relates specifically to my head, shoulders, hips and feet.  While it appears that the mummy style cut or design reduces the overall weight of the mattress, I question whether it will also be less comfortable for me as I tend to toss and turn at night.  As such, I will be checking my ability to move around and sleep in various positions without falling off the ProLite 4.  Toward the end of the testing period, I plan to wash the ProLite 4 following manufacturer instructions just to see how it fares.

Additional Biographical Information: