The purpose of the study is to evaluate the measuring accuracy of the Wristband for registration of ECG RR intervals for one hand, SenceBand icompared to the Holter monitor (LabTech Ltd).

Non-randomized, prospective, open clinical trial . The main purpose is to evaluate the measuring accuracy of the Wristband for registration of ECG RR intervals for one hand, SenceBand in real-world condition during 24-hours of routine duties in comparison to a predicate device (Holter monitor). For monitoring HRV each subject will put heart rate monitor SenceBand in the randomly assigned wrist and Holter monitor electrodes will be placed in standard configurations places. Data will be collected during routine duties. SenceBand will collect data from 5-minutes intervals each 30 minutes, Holter will collect data continuously over 24 hours.

Inclusion Criteria:

1. Subject has given written informed consent;
2. Subject is male or female, aged 18-75;
3. Subject has understood and complied with the requirements of the study protocol and;
4. Subject is fluent in Ukrainian.

Exclusion Criteria:

1. Subject has cardiac pacemakers;
2. Subject is a pregnant woman;
3. Subject has an allergy on polyurethane;
4. Subject refers to vulnerable groups of the population;
5. In investigator's opinion subject is not able physically or intellectually to fulfill the requirements of protocol.