The PulseTracker Plus features a unique S strap to meet the small chest-size needs of elementary-school students. We took it a step further by making it both easy and affordable to buy additional elastic straps in the other size to fit those students who are larger or smaller than the majority of their classmates. PulseTracker Plus also offers you another advantage lower battery costs. The financial and program impact of factory-required battery replacements for your heart rate monitors is a big consideration. PulseTracker Plus is color-matched to its transmitter, and then, with the purchase of optional sets of TrackerBands (available separately), you can group students by up to 6 colors. PulseTracker Plus is made for chest sizes 26" and larger and offers you all the features of an EKHO E15 at a competitive low price.