The polar infra red interface usb is great for when yoursquove completed your training and yoursquore ready to view the results using the polar protrainer 5 software the polar infra red interface usb provides that link by enabling a two way infrared data communication between your polar product and pc this is ideal for a good workout as by only reviewing your results at the end of a session yoursquore not getting distracted during your workout wondering where yoursquore up to you can