How to Use an Emergency Signaling Mirror

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How to Use an Emergency Signaling Mirror

A signaling mirror is a simple, effective means of communication and an indispensable item in your every day carry bag. We’ll review two brands of signal mirror — the Adventure Medical Kits Rescue Flash, and the Ultimate Survival Technologies Star Flash.

The Rescue Flash on top, the Star flash on the bottom


Why use a signal mirror

On a clear, dry day, a signal mirror can project an attention-getting signal as far as 15 miles. And if you’re looking for the signal, expecting it, you can spot it up to 20 miles away. Rescue teams, first responders, air and sea pilots, and military personnel are all trained to recognize intentional reflective signalling as a distress call. In addition, there’s a large community of

Instructions on the back of the Rescue Flash

preppers, survivalists, boy scouts, retired servicemen, hikers, campers, and on and on, all of whom will react to a signal mirror. Put all that together, and you’ll see that a signal mirror is a highly effective means of getting yourself noticed, particularly if a search and rescue is on, but even if it’s not.

Any reflective object can be used, but signal mirrors are designed to make targeting your flash a lot easier. They have a hole in the middle with a retroreflective surface that allows you to train a bright indicator on your target, so you’ll know for sure that you’re shining in the right place.

Geek bonus: How the retroreflective surface works

Most retroreflectors we’re familiar with are the kind that reflect light back to the source — we see these on automobile tail lights, road signs, and safety clothing. The mesh material in the mirror’s central hole is a type of retroreflector; it reflects light through the hole at an angle that is supplementary to the sun’s angle of reflection on the mirror. (The angle of reflection is equal to the angle of incidence, but lies opposite the surface normal). That causes

Looking through the aiming hole, shine the mirror on a nearby object, like your hand, and find the bright dot on the retroreflective material in the aiming hole. Then move the dot to the distant object you want to signal

some light to shine into your eye in a direction 180 degrees opposite the direction in which the mirrored surface is projecting its signal. The practical result is that when you see a bright dot superimposed on the horizon, a house, a plane, or your hand, you know that that’s where the flash will be seen. Because the mesh is rather coarse, there is a lot of empty space through which light is transmitted normally as well, so you can also see the world through the hole as it really is. In short, the retroreflective material allows you to co-witness the dot and the target. Finally, the retroreflective material attenuates the sun’s light, so the indicator dot doesn’t damage your eyes.

Description of the signal mirror

The Rescue is 2″ by 3″ and the Star is 3 x 5, but it also available in the smaller size. Both are made from Lexan, a brand of polycarbonate plastic that is very tough, but not very hard. It won’t break, but it will scratch, which diminishes its reflective ability. You should protect your mirror by keeping it in a plastic sandwich bag.

Both mirrors come with printed instructions on the back, both have lanyard holes, and both have a retroreflective aiming aid in the center.

The Star’s retroreflective material is a relatively opaque white material which is more difficult to use than the one on the Rescue because you can’t see your target as easily. The Rescue’s retroreflective material is far more transparent. This doesn’t matter in high-contrast situations, like if you’re aiming at an object in a clear sky or on the horizon, but if you’re trying using the Star to signal a house down in the valley, you might have a hard time spotting it. It’s not by any means impossible, it’s just harder than with the Rescue.

The Ultimate Survival Technologies web site advertises that the Star mirror will float, but when I tested it, it sank. I contacted the company, and they explained that only the smaller, 2 x 3 model actually floats, although at publication time this was not specified on their web site.

How to use the signal mirror

WARNING: Don’t shine the mirror directly into anyone’s face unless he’s a mile away or more!

Put the mirror up to your face with the aiming circle about one inch from your eye, and look through the hole (but not directly at the sun, of course!).

The signal produced by the mirror is unmistakable. This picture gives you some idea of why it can be seen from many miles

Reflect the sun onto a nearby target, like a boulder or even your hand. When your eye is in line with the target and the aiming hole, you’ll see a bright spot on the retroreflective surface.

Now move the mirror toward the object you want to signal, whether it’s a boat, a distant house, or an airplane. As you move, keep the bright spot in view, and when the dot is on your target, the reflection will be too.


Whichever one you choose, we found the smaller mirror to be just as effective as the larger one at generating an attention-getting signal at 1.5 miles. There might be a noticeable difference at greater distances, but we didn’t test this. Because the Star has a retroreflective surface that makes it more difficult to find the target, I prefer the Rescue Flash.


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  • David gilmasher Gilchrist

    Great video, Manny. I’m gonna have to pick up one of them there gadgets. Thanks for the info. and keep up the good work.

  • R.A. Fowell

    The Rescue Flash is a great signal mirror. I have used many signal mirrors, but this is the one I carry on me at all times. It is the lightest, thinnest signal mirror I've found with a high quality mesh retroreflective aimer. That aimer makes it infinitely easier to hit a target at long range.

    Two tips on using it :
    (1) remove the clear protective film from the front (and sometimes, the back) before using it (and replace it afterwards)
    (2) make sure nothing is putting your mirror in the shade, such as your cap brim (flip your cap around), hat, or a tree.

    Here's a video my wife made of the flash from my Rescue Flash mirror at 11 mile range: and one I made of my friend signalling at 22 mile range:

    There's a nice tutorial on aiming the Rescue Flash by its designer here:
    and a long discussion of its development about halfway down this page:
    in the section titled: "Rescue Flash™ Signal Mirror:"

    Glass signal mirrors, while heavier, are brighter and harder to scratch, so good for practice. When I'm in the wilderness, I carry a glass signal mirror in addition to the Rescue Flash. The Coghlan's 2"x3" glass signal mirror is sold at REI and many other places. The old version has a metal grommet in the lanyard hole, and is not watertight, but the newer version (sans metal grommet) survived several scuba dives just fine. The Vector I glass mirrors and the military issue MIL-M-18371E glass mirrors made by S.I. Howard Glass are also good. Beware of imitations that look like the real deal, but whose grids aren't retroreflective and don't create the aiming spot floating in space. For an article about the imitations, see this article:

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  • Insel Affen

    I’ve not seen the video (IPad not working properly) but the signalling mirror I have (British military issue) had a little lollipop stick attached to a 12inch string. You then sight the reflection on the back of the stick which ensures you hit your target, you could use your thumb instead, it really improves accuracy and speed, both are critical.
    Chris (AKA – Insel Affen)

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  • ScienceAdvisorSteve

    I don’t see a video either. It needs to be stated more obviously that the spot you see on the back of the mirror is a reflection of the sun shining through the hole onto YOUR self. I don’t see that in several explanations. One I saw even just looks for the beam on the target and ignores the most important part of the aiming principle.

    Watch these:
    Mr. Wizard explains:
    Military explanation @ 3:30 here:

  • ScienceAdvisorSteve

    I should have added that there is no need to shine the mirror on your hande when the proper technique is used.

  • ScienceAdvisorSteve

    Is this going to be fixed with the proper technique for aiming a signal mirror? This is sad.

    • Richard Fowell

      This is an “apples and oranges” issue – this site and your discussion are addressing two totally different types of signal mirror. This site provides the correct instructions for using a signal mirror with a retroreflective aimer, like the Rescue Flash and Star Flash. You provided (below) the correct instructions for using a double-sided signal mirror with a hole in it. Your technique won’t work with a single-sided retroreflective aimer mirror, and this site’s instructions won’t work with a double-sided signal mirror with a hole in it. Readers – take note – make sure the signal mirror you are trying to use matches the set of instructions you are trying to follow. For what it is worth, while the double-sided mirror approach works pretty well, if you have a choice, get a retroreflective aimer mirror – the US military switched from double-sided mirrors to retroreflective aimer mirrors ca. 1945.

      For the curious – if you want to know more about these two aiming methods (and the third, “foresight” method, this 1946 paper discusses the evolution of US military signal mirrors through WWII:;view=1up;seq=135

      For more tutorials on using retroreflective aimer signal mirror, see:

      For the double-sided mirror method, see:

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