Is the portable handheld cell phone signal jammer effective? What is the actual effect?

Is the portable handheld cell phone signal jammer effective? What is the actual effect?

The hand-held mobile phone signal jammer (portable cell phone jammer) adopts foreign advanced technology and is mainly aimed at small places that require security and confidentiality at home and abroad, such as private bosses, confidential offices, negotiation rooms, mobile vehicles, Mobile political and business dignitaries guard the scene, etc., according to the actual situation of mobile communications at home and abroad, a high-tech product that has been carefully developed. It can block GSM/CDMA/ DCS/PHS/3G mobile phone signals make it impossible for mobile phones in the area to make and receive calls, and will not interfere with the work of other electronic devices in the environment. When the phone is far away from the shielding range, it can resume normal use.

8 Bands Handheld GPS WiFi 2G/3G/4G Powerful Cell Jammers