Tested in a snow trench at 18°F, and the seams held. The Tact Bivvy 2.0 is a tough winter kit bivvy, if you can live with frost inside. It scores 78 out of 100 and ranks #4 in our best emergency bivvy guide as our best backup for winter packs.
Best Backup for Winter Packs
Tact Bivvy 2.0
- Weight (our scale): 4.8 oz
- Packed size: about a hockey puck
- Breathable: no
- Coldest night: 18°F
Bottom Line : Kept Ryan's core warm in a Black Hills snow trench at 18°F, and the seams held. Frost formed inside by 4 AM.
Pros
- Kept his core warm at 18°F
- 100% windproof
- Seams held against boots and thrashing
Cons
- Extreme condensation: frost inside by 4 AM
- A little harder to use than the others
In the Black Hills
Ryan used the Tact Bivvy during a March cold-weather drill in the Black Hills, South Dakota, at 18°F with wind-driven flurries, inside a snow trench.
The reflective film kept his chest and core warm, and the sealed seams stopped the freezing wind.
He thrashed around in it and the reinforced seams held against his boot soles. It weighed 4.8 oz and packed slightly bigger than a hockey puck.
Where It Asks Something of You
Condensation was extreme. His breath and sweat condensed on the silver lining and froze into a frost glaze by 4 AM. It also scored lowest of the four for ease of use.
Spec Sheet vs Our Test
Reflects 90% of body heat. The maker says the HeatEcho film reflects 90% of body heat. It kept Ryan's core warm at 18°F, and like every foil bivvy it trapped his moisture, which froze.
Weighs just 4.8 ounces and compresses small. The maker says it weighs 4.8 oz and packs into a small stuff sack. Ryan's scale agreed, and it packed slightly bigger than a hockey puck. That's small enough to forget about in a winter pack, which is exactly where a backup bivvy should live.
Incredibly durable. The maker claims it's surprisingly strong for its thinness. The seams held against boots and thrashing in the snow.
Should You Buy the Tact Bivvy 2.0?
Yes, as a light backup bivvy in a winter pack. It kept Ryan's core warm at 18°F and its seams held up to rough use.
Know what you're getting: in hard frost it will be icy inside by morning. For a long night, or a car kit, Ryan's own choice is the breathable SOL Escape.
Compare With
- SOL Escape Bivvy: our best overall emergency bivvy.
- SOL Emergency Bivvy: our best pocket bivvy.
- Go Time Gear Life Bivy: our best survival extras.
See all four, and how we tested them, in our best emergency bivvy guide.
Editor's Note, 17 October 2026: New review, from Ryan's field notes. He spent a real night in this bivvy and weighed it on his own scale.
Our Testers
This review was edited by Sean Williams and tested by Ryan Williams.
- Sean Williams, Editor-in-Chief. Sean built the team of researchers and testers behind our reviews and sets the rule the site runs on: we buy what we test, and we say what we found.
- Ryan Williams, Lead Tester. A heavy fleet equipment mechanic by trade, Ryan tests our generators, family tents and emergency gear.
