Holter system is designed and developed by Shenzhen ECGMAC Medical Electronics Co., Ltd. This product is mainly composed of Recorder Holter software and accessories. The recorder has 12 channels and 3 channels . The Holter software can handle the 12 leads ECG data of 12 channels recorder and 3 leads ECG data of 3 channels recorder, and the record of 3 and 12 channels data can be coexisted in a Holter software. Recorders are internally powered are intended for 24hours ECG recordings, on 3 leads or 12 leads Recorder is safe for patient with a pacemaker, the ECG recording is not affected by pacemaker pulses.