Choose inner and outer signal jammers?

So, which is better, the built-in or the external cell phone jammer? The answer must be the external phone signal shielding device shielding effect is good, because the built-in antenna gain is small, low power, on the contrary, the external antenna gain is large, .

There is another important difference between the two: the built-in antenna phone signal shielding device is easy to carry and plug in and use, each has its own advantages, you need to choose the right product according to your own needs.