This is a COROS heart rate sensor. I used it for about 15 minutes once after purchasing it, and then immediately switched to a different sensor. Therefore, it has hardly been used, but please refrain from purchasing if you are overly concerned about its condition. Please check the photos for the condition. The dedicated charging cable, original box, and instruction manual are included. Official information below: https://jp.coros.com/heart-rate-monitor - More comfortable and better fit than chest heart rate sensors - Adjustable fit, easy sensor removal - High precision with the latest multi-channel optical sensor - Can connect to up to 3 Bluetooth-enabled devices simultaneously - Equipped with wearing detection function, can be paired automatically - 38 hours of continuous operation, 80 days in standby mode - Charges with a magnetic USB cable The COROS heart rate sensor is compatible with various Bluetooth-enabled devices. It provides highly accurate heart rate measurement and offers approximately 38 hours of continuous operation, so you don't have to worry about running out of battery. Sophisticated Design & Comfort The COROS heart rate sensor uses soft band fabric. It's easy to attach to your forearm or upper arm, making it simpler than wearing a chest heart rate sensor. The slim design prevents it from catching on clothing or gym equipment, and it's so comfortable you'll forget you're wearing it, allowing you to focus on your workout. Adjustable Fit You can slide the buckle to adjust it to the optimal position. It's a Velcro type, so it's easy to remove when washing. Latest Sensor The latest multi-channel optical heart rate sensor provides highly accurate heart rate measurement. The scratch-resistant and protected sensor housed in a sophisticated body provides reliable and accurate heart rate data on a daily basis. Excellent Band High-precision measurement functions by securely fixing the optical heart rate sensor to the skin. The COROS band is designed to fit snugly against the arm, preventing external light from entering the sensor. Amazing Operating Time The COROS heart rate sensor has an operating time of 38 hours on a single full charge, and the power will not turn off for 100 days when not in use.