The Mountain Hardwear Phantom Spark is a fireball of three season bag. Our experts concluded that it was more closely related to 25F rated models, and potentially a tad warmer than most 30F. What impressed us most is the warmth that this model packs in for its weight. The Phantom Spark archives this by only using top-notch materials and down quality, coupled with a minimal design, and a slightly tighter-than-average cut.
The Phantom Spark uses 10.1 ounces of 800+ fill down to achieve its 28°F temperature rating and is on the warmer side of 30-degree bags. While it's rated as such, our testing team agrees with the rating. During our real-world testing, we found that this model was noticeably warmer than nearly all of the other 30F bags we tested (and even a majority of the 25°F models).
The Western Mountaineering MegaLite offered comparable warmth for a similarly rated model. The Phantom Spark offers a slightly-above-average amount of insulation for its temperature rating. When you take into consideration the amount of insulation, coupled with its slightly higher-than-average dimension, you end up with a fireball of a sleeping bag, especially for its temperature rating.
The Phantom Spark is perfect for backpackers and climbers who might typically purchase a 30°F bag but run on the colder end of the spectrum. Conversely, it's great for summertime alpine climbing or higher elevation backpacking where weight is crucial, but you still need something warmer than your average 30°F bag.
The Phantom Spark 28 weighs in at 1 lb 6.9 oz for a regular length model. This is decent for a bag with 10.1 ounces of fill, which is on the warmer side of most 30F bags and comparable to many 25F models. The Phantom Spark keeps the weight low in a few ways; most significantly, it's been constructed with 10D fabric that weighs a scant 26 g/m² and was tied for the lightest/thinnest in our review.
This 10D shell fabric is even lighter than the 12D exterior used by Western Mountaineering. In fact, the only other bags to use 10D fabrics were the Marmot Phase and the Sea to Summit Spark. Some people's first question will inevitably be, Well isn't the thinner fabric less durable? The simple answer is Yes, but in reality, and after extensive real-world testing, it is durable enough, and its thin shell fabric is still downproof. We also didn't notice it leaking more down than any other model in our fleet, though we did see less leakage than some of the other contenders. 10D isn't super tear resistant, but 12D isn't much better.
In reality, your sleeping bag doesn't need to stand up to much in the way of abrasion, though this bag still offers a fair amount of durability. The Phantom Spark's internal dimensions are tighter than average. However, in return for sacrificing a few inches of interior girth, the user will then gain thermal efficiency, which saves weight in excess material. The bottom line of the Phantom Spark's weight is that it's lighter than many 30F models, yet still offers more warmth. It does sacrifice a bit of interior space, but not much for those used to using performance-oriented mummy-bags. For those looking for the lightest possible bag without having to give up much in the way of warmth, the Sea to Summit Spark III is a 25°F model that is around one ounce lighter and offers a similar level of warmth.
With dimensions of 59", 53", 38 inches, the Phantom Spark is on the lighter side of models we reviewed, just barely offering smaller dimensions than most other performance-oriented mummy-bags. This model's dimensions are smaller than the Marmot Phase 30 or Western Mountaineering SummerLite, and is similar to the thermally efficient Western Mountaineering UltraLite.
While the Phantom Spark doesn't offer a much for interior space, all of our testers agree its interior fabric is one of the more pleasant feeling in our review. It feels cozy against our bare skin, warms up quickly, and feels significantly less clammy on warm nights (than other models we tested).
The Phantom Spark is geared towards being as light and compressible as possible, while still ensuring its a 30-degree bag. It features high quality down, thin 10D fabric, and minimal features, which help it maintain a minimum packed volume while remaining a respectable weight.
Despite offering more insulation and subsequently carrying a warmer temperature rating, the Spark packed down smaller than all but two of the 30°F models. The two exceptions were the Western Mountaineering SummerLite and the Marmot Phase 30.
This is even more impressive when you take into account this model is nearly half the packed volume of 30F models, like the comfort-oriented NEMO Disco 30 or the Kelty Cosmic Down 20. It is worth noting the 25°F Sea to Summit Spark III offers a comparable packed volume.
This bag offers excellent versatility when compared to higher-end mummy bags. It's light and compressible enough to be used for nearly any backpacking adventure but still warm enough for summertime mountaineering or for pushing the shoulder seasons of traditional three-season backpacking.
Its compressible size makes it suitable for bike touring or any other camping trip where packed volume is at a premium. Its okay for car camping, but its tight dimensions and higher price may better serve those heading out on backpacking trips. If car camping is your primary goal, there are plenty of other less expensive and roomier options available.
This model is designed with low weight and minimal packed size in mind; nearly all of its design attributes are geared toward this. It does, however, have a few small designs that make it easier it use. The Phantom Spark features one small zippered pocket that also doubles as a Velcro flap as a place to store your watch near your head, so you are more likely to hear your alarm go off.
All of our testers found its hood was comfortable, thermally efficient, and easy to adjust. Unlike most bags out there, this model comes with a compression sack, not just a stuff sack, which is an excellent addition to a storage sack. One minor point is of all the super-light models, the Phantom Spark's main side-zipper snagged the least; however, we do want to point out that it did still snag - just a lot less than other models, like the Marmot Phase.
The Phantom Spark 28 is perfect for those looking to save weight and have an exceptionally compact bag, yet not give up much in the way of warmth. The Spark is perfect for long, or short-range backpacking, even into the shoulder seasons. It also excels during summertime mountaineering in the lower-48 or southern Canada.
At $400, this bag is in line with similar bags of exceptional quality. It uses top-level materials and down and is the same price as the similar Marmot Phase 30. However, the Spark is warmer but not as compressible. It's similarly priced to the 32F rated SummerLite, though the Spark is warmer. The Western Mountaineering MegaLite has much more comfortable interior dimensions and comparable warmth but isn't near as lightweight.
Overall we find the Phantom Spark to be an excellent value. We found its build and craftsmanship to be quite good, its 800 fill down should last 20 years or more if well-taken care off and while on the spendier side we think that this models performance characteristics easily justify the price.
