Hi I had one of these a few months back. You go to the hospital and they put the a blood pressure band around your arm attached to that is the monitor, which is attached to a belt that goes around your waist, you can take that of at night and put it on a bedside cabinet. It then takes your blood pressure every hour and 2 at night. You will know when its working as the monitor will bleep and the band will start to inflate. It should'nt hurt you. The nurse will make sure it inflates properly when first attached, just make sure its not to tight for you.