Feature: 1. This product uses a high-performance dedicated microcomputer chip as the core, which can alarm bell automatically according to user settings. 2. A maximum of 20 groups in single ring mode and 40 groups in dual ring mode can be achieved in one day. 3. Accurate time and easy operation. Widely used in schools, companies, institutions to control the automatic bell. 4. Powered by 1 x AAA battery (not included), convenient for battery replacement. 5. Easy program, everyone can program it after he reads the manual just one time. Specification: Condition: 100% Brand New Item Type: Microcomputer Timer Switch Material: ABS Color: As Pictures Shown Working Power: 220V / 50Hz Applicable Voltage Range: 180 - 240V Dissipated Power: Less than 5W Timing Error: Less than ± 2s / day Ring Time: 0 - 99s adjustable Double Bell Interval Time: 0 - 99 minutes adjustable Power Supply: 1 x AAA battery (not included). Package List: 1 x Microcomputer Timer Switch1 x Manual Note: When the screen is unclear or no display, please replace the battery in time.Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.