This was purchased from Amazon in 2018 and is in full working order, you remove the straps and plug it into a USB point to charge it. I have charged it and found out you can get instructions for it on the internet.
It tracks Heart rate, is waterproof, sleep monitor, pedometer, calorie counter and can be used with an iphone. You can still buy them from Amazon.
Delvfire Watch and Fitness Tracker HR (Lydiard Millicent SN5)
This offer has been gifted to someone and is no longer available.