Helps achieve better time management by allowing people to see elapsed time in sound-sensitive environment. Time exercises, teaching sessions, meetings, homework, duration drills, tests, etc. Time elapses clockwise and can be set at any point from 0-60 minutes. Uses one AA battery (not included). The 8 (20cm) or 12 (30cm) square Time Timer can be freestanding or wall-mounted. The Personal Time Trainer is 3 (8cm) square and features a protective cover, tough nylon carrying case with Hook & Loop closure, and belt loop.