A man experiences a sighting telescope at the 8th China International Exhibition on Police Equipment in Beijing, capital of China, May 17, 2016. The four-day exhibition kicked off at China National Convention Center in Beijing Tuesday. (Xinhua)

People visit the 8th China International Exhibition on Police Equipment in Beijing, capital of China, May 17, 2016. The four-day exhibition kicked off at China National Convention Center in Beijing Tuesday. (Xinhua)

A man experiences a drone interception device at the 8th China International Exhibition on Police Equipment in Beijing, capital of China, May 17, 2016. The four-day exhibition kicked off at China National Convention Center in Beijing Tuesday. (Xinhua)

Photo taken on May 17, 2016 shows a hoolivan at the 8th China International Exhibition on Police Equipment in Beijing, capital of China. The four-day exhibition kicked off at China National Convention Center in Beijing Tuesday. (Xinhua)