For the most accurate core body temperature measurements, CORE is worn on the chest. The chest strap is a convenient and reusable solution for wearing the CORE discretely for extended duration and particularly for sporting activities. The chest strap is made of soft stretchable nylon that can be easily washed and reused. The adjustable strap accommodates a wide range of sizes and is one-size-fits-all. This chest strap is an alternative to the medical-grade patches and when using the black fastening clips (which are provided with the CORE), is a reliable method to secure CORE for active and sports-use. Please note, this strap does not include a Heart Rate Monitor and does not include the CORE which is shown for demonstration. CORE can be purchased separately.