When Microsoft killed its Band wearables, a leak emerged of what was believed to be the cancelled third-generation model. Well, it's real -- and it says a lot about what Microsoft was thinking before it pulled the plug. Windows Central has obtained a Band 3 prototype and given it a shakedown to see how well it would have worked. True to the rumors, the biggest deals were the additions of waterproofing, swim tracking and (most importantly) an electrocardiogram sensor to track your blood pressure. We now know that the Band 3 could tell if you were stressed out, check your body temperature or otherwise track your health beyond fundamentals like heart rate and calorie burn.