CSF-3 is a wrist-worn medical device similar to a watch. It is designed to monitor a user's heart rate based on ECG (electrocardiogram) and PPG (Photoplethysmograph) readings, using off-the-shelf ECG and unique PPG chipsets with proprietary algorithms. ECG and PPG are the two primary technologies for measuring heart rate. ECG measures the bio-potential generated by electrical signals that control the expansion and contraction of heart chambers, while PPG uses light-based technology to sense the rate of blood flow as controlled by the heart's pumping action.

The proposed clinical study is a prospective, open, single-center study to evaluate the performance and accuracy of the ECG and heart rate calculation of the CSF-3 investigational Device.

Subjects will be screened by the Principal Investigator. Subjects who meet the study's enrolment criteria will be recruited and fitted with an FDA cleared ECG Holter, and with the investigational Device (CSF-3).

At least 40 eligible subjects will be enrolled in a single center. Data collected from the subjects during the study will be included in the overall performance analysis of the ECG output. Subjects will perform an ECG and CSF-3 Device simultaneously Subjects will remain connected to both the ECG Holter and the CSF-3 Device at the study site for at least 7 minutes duration. The ECG and Holter will be stopped simultaneously. Both recordings data (ECG and CSF-3) will be uploaded and then synchronized offline using a dedicated and validated tool.

Inclusion Criteria:

• Age ≥ 21 years old
• Able and willing to understand and sign the informed consent and follow instructions
• Screening ECG results of Sinus Rhythm
• Wrist size 14 cm (5.5"), Max 20 cm (7.8")

Exclusion Criteria:

• Subjects who are currently enrolled in other clinical investigation
• Subjects diagnosed with a cardiac disorder or any cardiac symptoms
• Subjects with SNR < 100
• Subjects with ECG quality range > 1 and < 30
• Individuals with electrical pacing by a pacemaker
• Subjects who are pregnant or breastfeeding
• Subjects with callous on the index finger or thumb (at fingerprint area)
• Subjects with active wound, prior soft tissue injury or skin conditions at the measurement location Sensitivity to the device material or ECG patches
• Subjects with tremors or otherwise unable to remain still for 15 minutes
• Subjects without two hands and sufficient fingers to complete the study
• Subjects unable to participate based upon investigator discretion