Many studies have now confirmed that blood pressure measured over a 24-hour period is superior to clinic blood pressure in predicting future cardiovascular events and target organ damage. 

It’s mainly for pediatric hypertension, but a good reference on the subject. It is important to understand the application of the device and how it can benefit the patient and the doctor in diagnosis and treating hypertension.
Echo80 Ambulatory Blood Pressure Monitor is a great product to start 24 hour BP monitoring with.