The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Woerk ApS:
Turn your iPhone into a real heart rate monitor with Heart R8.Place your index finger in front of the iPhone camera and within 10 seconds your current heart rate will be read and logged to your history.Since it calculates your heart rate due to blood flow in your index finger the best results will be when your hands are naturally warm. In cold weather there can be slight difference in readings.The heart rate monitored and logged should be within 1-2 bpm of any HR running measuring devices or regular medical oximeters.Press gently and cover the lens with your finger. If you finger is placed correctly the reading will be more accurate. Correct placement will be indicated by 5 dots on left side of the start-up screen.* Medical DisclaimerNothing contained in this application is entended to be used for medical diagnosis or treatment.It should not be used in place of the advice of your physician or other qualified health care provider.