The Kendall™ H124SG is a disposable, pre-gelled adhesive electrode. A pair of Kendall™ H124SG allows you to conveniently connect both CMS (Common Mode Sense) and DRL (Driven Right Leg) mandatory reference electrodes the bare skin mastoid to achieve high-quality electrical reference of the EEG/tES system. Additionally, it can be used for ECG, EMG or EOG (when placed near the eye).