Handheld security scanners are a product that may never go out of use. They perform such a vital purpose: detecting both ferrous and nonferrous metals that could be built into all sorts of weapons hidden in purses, backpacks, etc. These devices have proved effective for decades, and there is no reason to believe police agencies and security teams will stop using them any time in the near future.
The principle of the hand-held security scanner is rather simple. The device emits an electromagnetic wave that is then reflected back almost instantaneously. That wave is capable of detecting metal objects. Should the detector pick up on something, it generates an alarm to alert the user. The user can then determine whether a more thorough inspection is warranted or not.