Features: 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_x000D_ Item Type: Microcomputer Timer Switch_x000D_ Material: ABS_x000D_ Color: As Pictures Shown_x000D_ Working Power: 220V / 50Hz_x000D_ Applicable Voltage Range: 180 - 240V_x000D_ Dissipated Power: Less than 5W_x000D_ Timing Error: Less than 2s / day_x000D_ Ring Time: 0 - 99s adjustable_x000D_ Double Bell Interval Time: 0 - 99 minutes adjustable_x000D_ Power Supply: 1 x AAA battery (not included) PackageList: 1 x Microcomputer Timer Switch1 x Manual Note: When the screen is unclear or no display, please replace the battery in time._x000D_ 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.