How to avoid being noisy in the library

When I was studying in the library, the phone rang. Some people are listening to the concert. Some people cheat on their mobile phones at the exam site. Some people worry about information leakage. These phenomena are very common. Many people are in trouble. I want to take measures. Is there any device that interferes with the telephone signal? How is the quality of the product? What is the barrier range? Which product do you choose? Many people have various problems. We will introduce countermeasures against these problems. We will explain our latest armament cell phone jammer. Recently, we designed a camouflage jamming device for ammunition based on customer needs. Currently, it is sold on this site. Evaluation is also the best product. This product is a new product developed according to the actual situation of mobile communication using foreign advanced technology. This kind of mobile phone jammer has its own characteristics. In appearance, it uses the camouflage design of ammunition. The color of the product is very beautiful. Previous products usually had a black appearance. The color of the product is sober. In addition, there is an LCD display. The previous product did not have an LCD display. This is also the function of the product.