The Emergency Bivvy That 213+ Verified Buyers Rate 4.91 Stars
NASA Mylar technology that retains 90% of your body heat - tested warm at 32°F by real customers. Only 6 oz. Smaller than a soda can.
See How It Works
NASA Mylar technology that retains 90% of your body heat - tested warm at 32°F by real customers. Only 6 oz. Smaller than a soda can.
See How It Works
Here's something most hikers don't think about until it's too late:
That $8 emergency blanket in your pack? A verified customer tested it at 32°F. It tore within minutes.
The Sierra Madre Emergency Bivvy? Same test, same temperature. The customer reported being "just fine, warm."
That's not marketing. That's a real customer, real conditions, real results.
The difference is NASA technology. The same Mylar material that protects spacecraft from -250°F in the shadow of Earth. Now it fits in your pocket for $34.
Here's an uncomfortable truth:
That $8 emergency blanket is designed to sell, not to save.
We know - it feels responsible. You bought it, packed it, and it gives you a sense of security. But here's what actually happens when you need it:
The question isn't whether you'll ever need emergency gear. The question is whether your gear will work when you need it.
This isn't marketing fluff. It's NASA engineering.
The Emergency Sleeping Bag uses Mylar - the same material NASA developed for spacecraft insulation. When astronauts needed protection from -250°F in the shadow of Earth, they turned to reflective thermal technology.
Your body produces approximately 100 watts of heat at rest. The Sierra Madre bivvy reflects 90% of that heat back to you through the same principle that keeps satellites from freezing in space.
That same science now fits in your pocket for $34.
It's smaller than a soda can. It weighs 6 oz. And verified customers have tested it warm at temperatures down to 20°F.
Richard Rhett isn't a gear salesman. He's a Research Mechanical Engineer who spent months in the field before designing a single product.
After traveling the world - jungles, mountains, rivers - Richard was confronted with two problems:
So in 2010, Sierra Madre was born with a dual mission: create gear that would actually protect campers regardless of conditions, and use those products to fight the water crisis one well at a time.
Every purchase provides 1 year of clean water to someone in need.
That's not a marketing line. That's why Sierra Madre exists.
Best for: Hikers, backpackers, car emergency kits, and anyone who refuses to gamble with survival
Get Your Emergency Bivvy - $34| Feature | Cheap Mylar | Budget Bivvy | Sierra Madre |
|---|---|---|---|
| Heat Retention | 60-70% | 70-80% | 90% |
| Material | Thin mylar | Basic reflective | NASA-grade Mylar |
| Durability | Single use | 2-3 uses | 100+ uses |
| Waterproof | No | Partial | Yes |
| Weight | Varies | Varies | 6 oz |
| Visibility | Silver | Varies | Rescue Orange |
| Price | $8 | $15-25 | $34 |
| Verified Reviews | Mixed | Limited | 4.91 stars (213+) |
All testimonials from Judge.me verified purchase reviews
"Tried it outside at 32°F and was just fine, warm!"
"I bought multiple to hand out to unhoused people. As temps dropped into the 20's, these provided warmth and protection from the elements."
"It's smaller than a soda can but unfolds into this huge, waterproof thermal bivy."
"Great company with quality products. They come very compact and can be stashed anywhere."
"You talk to actual humans! Friendly humans! Very rare these days."
One verified buyer shared something that stuck with us:
"I bought multiple to hand out to unhoused people. As temps dropped into the 20's, these provided warmth and protection from the elements."
That's not what we designed the bivvy for - but it's exactly why we built Sierra Madre.
Every purchase provides 1 year of clean water to someone in need. Your emergency gear helps others survive too.
In an emergency, complicated gear is useless gear. The Sierra Madre Emergency Sleeping Bag is designed for one thing: keeping you alive with zero learning curve.
The compact pouch (smaller than a soda can) fits in any pack pocket or car glove box. When needed, pull it out and unfold.
Slide in feet-first like a sleeping bag. The bivvy design means no fighting with blanket corners.
The NASA Mylar interior immediately begins trapping your body heat. Within minutes, you'll feel the temperature stabilize.
When the emergency passes, fold it back into its pouch. Unlike disposable options, it's ready for next time.
Yes - when built with the right materials. The Sierra Madre uses NASA-developed Mylar that reflects 90% of body heat. Verified customers have tested it warm at 32°F and below. Cheap alternatives use thinner materials that retain only 60-70%.
A verified customer tested ours at 32°F outdoors and reported being "just fine, warm." Another bought multiple for unhoused people during 20°F temperatures. With 90% heat retention, you can maintain survivable body temperature for 8-12 hours in near-freezing conditions.
The math: $8 blanket that tears after one use vs. $34 bivvy that lasts 100+ trips and actually works. One verified customer said "worth every penny" after 12+ trips. Your life isn't worth gambling on equipment that might fail.
No - this is emergency backup gear, not a replacement for proper sleeping systems. It's designed to keep you alive in unexpected situations, not for planned camping comfort.
30-day satisfaction guarantee. Test it in real conditions. If you're not confident it would save you, return it for a full refund. No questions asked. Plus, Wildling Members get a lifetime warranty.
Take it on the trail. Test it in your backyard at 32°F like our verified customers did. If you're not completely confident it will keep you safe, send it back for a full refund. No questions asked.
Join 213+ verified buyers who gave this bivvy 4.91 stars.