# An emergency blanket is not a sleeping bag > Three thin Grabber blankets cut wind and take almost no space, so they belong in the car and the go-bag, not in place of a sleeping bag. Part of the [Shelter](https://bordernest.com/silo/shelter.md) guides. ## What the blanket actually does A mylar emergency blanket is a thin sheet of aluminum-coated plastic, and that is the whole object. It reflects your own body heat back at you, which is useful when the real problem is wind stealing warmth from a person who is already dressed for the cold. It weighs almost nothing, folds down smaller than a deck of cards, and costs very little, which is why a class handout will tell you to keep one in every car and every go-bag. None of that makes it insulation. It is a wind shell and a heat reflector, and once you understand that, the right place for it becomes obvious. ## Why it is not a sleeping bag The same thinness that makes it packable also makes it loud, easy to tear, and unable to trap still air the way a sleeping bag does. A real bag uses loft, meaning thickness and fluff, to hold a layer of warm air around you, and a sheet of foil has no loft at all. If you wrap one around yourself on a cold night you will feel a brief flash of warmth from the reflection, then the conductive chill of plastic against your skin as your body heat is pulled through the material. That is why a night spent under a mylar blanket on purpose, instead of by accident, usually ends with a miserable camper who learned the lesson the hard way. ## Where to keep them, and what to add The right home for Grabber mylar blankets is anywhere space is the limiting factor. A car trunk, a bug-out bag, a coat pocket, a desk drawer at work, and a child's backpack are all good answers, because the day you actually need one is the day your car is stuck on a shoulder in February or your kid is waiting on a soccer field after dark. Keep them where they will be reached without thinking. If you might genuinely sleep outside on purpose, whether that means a planned winter hike, a vehicle breakdown in a real cold snap, or a shelter situation that lasts more than a few hours, the object you want is a bivy sack, which is a thin nylon shell with a real insulating layer built in. Do this today. Open the trunk of the car you drive most, pull out the loose jumper cables and the random umbrella, and drop in one sealed mylar blanket so the next person who opens that trunk finds it without searching. **Grabber: Grabber Space Brand Emergency Blankets, pack of 3.** A pack of three so you can stage one in the car, one in the go-bag, and one at the office without raiding the others. ## The simple rule of thumb Blanket in the bag for the surprise night, bivy in the pack for the expected one. If you can stand up and walk to your car, the mylar is doing its job. If you are lying down and trying to sleep, you want loft, not foil. Your next read is A bivvy if the night might be spent outside. When you are ready to compare gear, open the See the shelter aisle. Links here are Amazon affiliate links. If you buy, we may earn a commission. It does not change your price. Check the live listing before you order. ## Related guides - [Stay in if you can. Carry a roof if you cannot.](https://bordernest.com/blog/shelter-hub.md): You stay home when the conditions allow it, and you carry a roof when they do not. This guide shows the two separate piles so your bag stays light and your closet stays useful. - [How to start a fire outside without cooking the yard](https://bordernest.com/blog/how-to-start-a-fire-outside.md): You clear dirt, start small, and keep flames away from the tent. Practice on a Saturday, not during an emergency. - [How to pitch a tube tent on the first try](https://bordernest.com/blog/how-to-pitch-a-tube-tent.md): A tube tent is a plastic sleeve and a cord, so pitch it between two trees once in daylight before you need it. You will learn where the plastic touches your face and where the floor puddles. - [A go bag and a stay-home pile do different jobs](https://bordernest.com/blog/a-go-bag-and-a-stay-home-pile.md): Two piles, two jobs: a heavy shelf for the house and a light bag for the stairs. The split is what keeps both useful when the lights flicker or the road closes. - [Where the home kit sits so you can find it](https://bordernest.com/blog/where-the-home-kit-sits.md): Ready.gov says put the home kit in a named place and tell the household. A closet people can point at beats a perfect list nobody opens. - [Pick the room before the siren does it for you](https://bordernest.com/blog/how-to-shelter-in-place.md): Pick an interior room on a calm afternoon, tape the plastic, and tell the house which room is the shelter before the siren makes the choice for you. - [Tape one room if the plan is to stay inside](https://bordernest.com/blog/tape-one-room-if-you-are-staying.md): A roll of tape and a sheet of plastic can turn one pre-chosen room into a cleaner-air pocket. The lesson is that the room is named on a calm day, not during the alarm. - [Plastic and tape for a single drafty window](https://bordernest.com/blog/plastic-and-tape-for-one-window.md): One drafty window, a roll of plastic, and a few minutes with tape. A focused fix that keeps cold air out of the room you actually plan to shelter in. - [Staying in an apartment when leaving is worse](https://bordernest.com/blog/staying-in-the-apartment.md): When the road outside is the hazard, the apartment becomes the shelter. Learn how to seal one room, stock water and no-cook food, and keep a radio within reach so you can wait it out safely. - [A bathroom plan that is bags, not a gadget](https://bordernest.com/blog/a-bathroom-plan-that-is-bags.md): A lined bucket and a bag you already know how to tie, set up in the room you already chose. Learn why the simplest sanitation plan is the one that actually gets used when the water is off. - [A 72-hour bag you would actually carry](https://bordernest.com/blog/a-72-hour-bag-you-would-carry.md): Three days on your back if you have to leave. So small bottles, a few bars, copies of your papers, a whistle, and a thin shelter. If you cannot lift it down the stairs, it is not packed. - [A work bag for one day you cannot get home](https://bordernest.com/blog/a-work-bag-for-one-stranded-day.md): A desk drawer can quietly hold the supplies that get you through one stranded workday, so a sudden disruption does not catch you without water, food, or walking shoes. - [A car kit for the drive you already make](https://bordernest.com/blog/a-car-kit-for-the-drive-you-make.md): A blanket, a snack, a whistle, and a way to be seen. So that covers the commute. If you leave the car and walk, you wanted the bag, not the trunk. - [Winter supplies that should already be in the car](https://bordernest.com/blog/winter-supplies-already-in-the-car.md): A driver sits in a cold car on a winter shoulder, learning which blanket, snack, and water choice actually helps when the engine is off and the temperature drops. - [A blanket that lives in the car](https://bordernest.com/blog/a-blanket-that-lives-in-the-car.md): Three thin blankets that live in the trunk and a clear-eyed look at what they actually do on a cold night. - [A roof you can carry, for the night in the car](https://bordernest.com/blog/sol-emergency-bivvy-for-the-bag.md): A reflective bivvy you can crawl into when the car becomes the room for the night. Practice the zipper in daylight so the dark is not the first time. - [A bivvy if the night might be spent outside](https://bordernest.com/blog/a-bivvy-if-the-night-is-outside.md): A roadside night with no tent calls for a heat-reflective bivvy you can crawl into fast. Students learn how the SOL Survival Bivvy traps warmth, why the whistle matters, and how to rehearse the zipper before they need it. Open the HTML guide to see today's Amazon listing. Prices are confirmed on Amazon. This is not medical, legal, or emergency-service advice.