And any handheld mirror or flat, shiny surface can be used to accomplish the task. Compact and simple to operate, it has been successfully used for many rescues. Any mirror or other shiny surface can be roughly aimed by reflecting sunlight through a V on one's outstretched hand. Sight through a hole in the mirror, or over the mirror, and through the V at a distant target. However, simple mirrors of this type are neither easy to use nor highly efficient for signaling.
Considerable practice is necessary to effectively use one as a reflective signaling device.
This can cause momentary blindness, resulting in an accident. More effective and user-friendly are the newer, specially designed plastic signal mirrors. They have a built-in aimer for easier, more precise focusing on a potential rescuer. These modern plastic mirrors can be used with one hand, are designed to float, weigh less than metal or glass mirrors, and are less easily damaged. To test a device of this type, reflect the sun at a shaded vertical surface at least 50 feet away.