COROS Heart Rate Sensor This is a heart rate sensor that you wear on your arm. I purchased it new on Amazon at the beginning of December and have only used it once. After use, I gently washed it with hand soap and dried it. I connected it to a smart trainer. The connection was easy and it connected immediately. The accessories are as shown in the first photo. It has only been used once, but please purchase it understanding that it is a used item.