Pager explosions in Lebanon: What are these devices that have caused wave of blasts

Smoke rises from a mobile phone shop in the southern Lebanese city of Sidon, after a second wave of device explosions hits the country. The blasts came a day after the simultaneous detonation of pagers used by Hezbollah killed 12 people, including two children, and wounded up to 2,800 others across Lebanon. The unprecedented attack is being blamed on Israel, though Israel has made no comment.