Reviewed in April, 2024

The MontBell Plasma 1000 (men’s / women’s) has one of the best warmth-to-weight ratios of any jacket we tested. If you’re an ultralight backpacker looking for the lowest weight for the most warmth, you can stop scrolling here.

At around eight ounces, the Plasma 1000 is perfect for long carries and packs super small for big adventures. It’s an all-time favorite of CleverHiker Founder, Dave Collins. He’s put over 500 miles on his Plasma 1000 including treks in Wyoming’s Wind River Range, Washington’s Olympic National Park, and Patagonia.

The Plasma is the only jacket on this list using 1000 fill down. This jacket is in a class of its own for warmth and loft – a dreamy combination for backpacking. It may weigh about the same as some of the other ultralight jackets on our list, but it certainly feels warmer. The Plasma is an ideal layer when sleeping on sub-freezing nights, while making coffee in the morning, and staying warm just before bed.

from CleverHiker

Reviewed in September, 2020

Among hardcore alpinists, you won’t find a brand with more street cred than Montbell. This Japan-based company makes gear for people who truly use it and doesn’t spend much effort on paid athletes or splashy marketing campaigns. But the proof is in the pudding: Montbell makes some of the best ultralight insulation on the market, and because it’s mostly direct-to-consumer, the costs are reasonable for what you get. Our favorite ultralight down jacket in their lineup is the Plasma 1000 Alpine Down Parka. With 1,000-fill-power down (no, that’s not a misprint) along with an ultra-thin 7-denier shell, it offers by far the best warmth-to-weight ratio on this list. It’s not the absolute lightest option out there, but it’s a well-balanced UL piece that weighs next to nothing.

from SWITCH BACK TRAVEL

Reviewed in August, 2020

■Warmth: 4.9

With temps in Utah’s Little Death Hollow hovering around freezing on a November trip, the Plasma 1000 kept us warm over a T-shirt and light fleece as we did camp chores. On ski tours in the Rockies, we paired it with a baselayer and midlayer for comfort into the single digits. While sitting around camp, we overheated in this puffy at around 55°F.

■Packability: 4.7

For a jacket with such a dialed feature set, the Plasma doesn’t take up much space. It leverages premium, 1000-fill down (it’s not hydrophobic, but still jacks the price up) to squish into an eggplant-size cylinder with its included stuffsack. This feat is all the more impressive given that it’s the warmest jacket in the test.

■Durability: 3.5

The 7-denier ripstop nylon is among the most delicate here, crinkly, and saw its share of dings over a season. While scrambling up boulders to get a photo of the night sky from Little Death Hollow, one sleeve suffered a small tear on a sharp corner; we experienced a few of these tiny snags over 5 months of testing, but they never spread and we patched them easily.

■Features: 4.7

A beefy, fully insulated hood (not helmet compatible) is adjustable on the sides and back. The Plasma 1000’s full zipper makes for easy on/off, and two zippered hand pockets keep your digits toasty and hold small items. A DWR treatment was welcome while we pushed through dewy brush, but it doesn’t hold up to more than a quick drizzle.

■Overall: 4.5

from BACKPACKER