1. First confirm the use place and area of the shield;
2. Confirm the shielded signal type: 2G/3G/4G/5G/2.4G/5.1G/5.8G, etc.;
3. Confirm whether there is a signal base station tower near the place of use or whether there is a signal amplifier in the corridor;
4. Confirm the extended function of the signal jammer: long-term power-on use/unified control switch/timed on/off/autonomous detection of whether the jammer is in normal use and other functions;
5. Confirm whether the jammer you purchased is a regular product. Do not buy three-no products. When purchasing a signal jammer for phone, you should check the manufacturer and ask about the warranty period and after-sales service;
6. When purchasing a product, check whether there is a test report and whether there is any radiation effect on the human body.