SK-2 cellular phone jammer is the most popular electronic information security instrument used in examination halls, examination rooms, test rooms, etc. The cellular phone jammer can help examiners to prevent students cheating with cellular phones in the examinations. SK-2 cellular phone jammer transmits low power radio signals to block the communication signal bandwidths of cellular phones in GSM, CDMA, PHS, DCS, etc. Beijing Signal Knight is a professional cellular phone jammer's manufacturer in China; we can design and develop any types of cellular phone jammers for different clients'demands. Nowadays, the cellular phone jammer has become the necessity for schools, universities, testing centers, and so on.