Naturehike SunTherm MS500 Review: A Washable Synthetic Sleeping Bag That Doubles as a Blanket

If you have ever stood in a gear aisle trying to decide between a stuffy mummy bag and a flimsy picnic blanket, the Naturehike SunTherm MS500 is aimed squarely at that gap. As someone who evaluates camping gear by the numbers on the spec sheet and the way a design fits real trips, I picked the MS500 because it is the top model of the brand's M Series, and because its feature list is unusually practical: it opens flat into a blanket, it zips to a second bag, and you can throw it in the washing machine. You can see the current listing at Naturehike and the store overview on our Naturehike store page.

The short version

The MS500 is a rectangular-style, openable synthetic sleeping bag priced at $79.99 in Gray, Green or Pink. The listing rates it at "27.4°F / 3°C," uses a 210T polyester pongee shell with a soft peach-skin finish, and carries roughly 1500g of washable synthetic cotton fill. It is built for car camping, family trips, cabins and cool-weather sleepovers rather than for ultralight backpacking. If that is the kind of camping you do, it deserves a place on your shortlist.

Specifications (from the manufacturer's listing)

How the M Series scales: MS100, MS300 and MS500

The same listing compares three siblings, and the comparison is the most useful thing on the page. The MS100 carries about 300g of fill and weighs roughly 0.96 kg; the MS300 steps up to about 900g of fill and 1.63 kg; the MS500 doubles down with about 1500g of fill and 2.39 kg. Open size stays at 220 × 80 cm across all three, so you are really paying for insulation, not for extra length. The MS100 is listed at $44.99 and the MS500 at $79.99, so the top model costs about $35 more. Whether that is worth it depends on how cold your nights get. As a rule of thumb from the fill weights alone, the MS500 holds roughly five times the insulation of the MS100, which is why I would only pick it if you expect genuinely cool nights.

What I like

1. The openable design is genuinely flexible

Because the bag opens fully, you can use it as a blanket on warm nights and zip it up when the temperature drops. That is a big deal for shoulder-season trips, where an evening at 60°F can become a morning near freezing. A fixed-shape mummy bag cannot do that.

2. Side zippers let two bags become one

The listing says two bags can be joined through the side zippers to make a double sleeping bag for couples or families. If you buy two in the same colour, you get a roomy shared bed without paying for a dedicated double.

3. Washable fill and shell

A sleeping bag that can go through the washing machine on a gentle cycle is a practical advantage, especially for kids' sleepovers and rental cabins. The synthetic cotton filling and 210T pongee are described as easy to clean while keeping their softness after washing. Synthetic fills also tend to tolerate damp conditions better than down, and the listing highlights moisture resistance of the filling.

4. A softer feel and a gentler fabric

Naturehike says the MS500 uses a premium synthetic cotton fill that is more breathable and softer than standard imitation down, and that the fabric is upgraded to infant-safe quality, formaldehyde-free and pH-neutral. For anyone with sensitive skin, or for parents buying for children, those are meaningful points, although you should still read the fabric label on arrival.

5. Reasonable pack size for what it is

Packed size is Φ32 × 40 cm. That is not tiny, but for a 1500g-fill bag it is respectable and fits in a trunk, a roof box or a large duffel without drama.

What I do not like (the real drawbacks)

1. It is heavy. At about 2.39 kg it is far outside backpacking territory. If you count grams, the MS100 at ~0.96 kg is the only member of the family that makes sense on foot.
2. The temperature rating is confusing. The product title reads "27.4°F / 3°C," but 3°C converts to about 37.4°F, not 27.4°F. One of those two numbers is likely a typo, and the listing does not say whether it is a comfort, limit or extreme rating. I would assume the more conservative 37°F figure until Naturehike clarifies, and I would not rely on it near freezing.
3. Bulk. Φ32 × 40 cm is fine for a car, but it takes up real room in a small tent or a carry-on bag.
4. Synthetic fill trades warmth-to-weight for convenience. You get washability and moisture tolerance, but you carry more weight per unit of warmth than you would with a good down bag.
5. Limited data. The listing gives no shell water-resistance rating, zipper brand or hood details, so I cannot confirm those points.

Who should buy it

I would recommend the MS500 to car campers, families, cabin owners, festival-goers and anyone who wants one bag that also works as a bed blanket for guests. It also suits people who want to splice two bags together for a couple. The washable construction makes it an easy pick for households that expect messy, kid-driven use.

Who should skip it

Skip the MS500 if you hike more than a mile from the trailhead, if you need a certified temperature rating for cold-weather safety, or if you want the lowest possible weight. In those cases, look at a compact down or ultralight synthetic mummy bag, or step down to the lighter MS100 or MS300 in the same family.

Verdict

For $79.99, the Naturehike SunTherm MS500 offers a lot of flexible, washable comfort for relaxed camping. It is not a lightweight or technical bag, and the confusing temperature figure deserves a clarification, but as a versatile, family-friendly option it makes sense. If you want a bag that works as a blanket at home and a bed outdoors, it is a sensible buy.

Where to buy

You can check current colours, pricing and availability on the official Naturehike page, and read more about the brand on our Naturehike store page.

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