The Scosche R24RABXL-HF extra-large (XL) replacement band is designed to work with your Scosche Rhythm 24 and Rhythm+ 2.0 and fit securely on your forearm, triceps, or biceps while swimming, cycling, running, or during intense gym workouts. The extra-large (XL) size also makes this band perfect for upper forearm placement. Its measurements are: 21cm max to 37.5cm min. The new quick-lock design eliminates velcro, buttons, or other fasteners that can fail in extreme conditions. About the Scosche Rhythm24, Train Smart, Get Fit. The nucleus of our health and fitness is the heart. Being able to accurately monitor, measure, record and transmit heart rate data over an extended period is essential to maximizing one's workout, whether it be running, cycling, swimming or working out in the gym. This is the very essence of Rhythm24. This next-generation, heart rate health and fitness device are highly accurate, packed with outstanding features and very comfortable to wear, so you can ditch those chest strap devices and now workout longer, in more places and in maximum comfort. This band is NOT compatible with the original Scosche Rhythm+.