SMA-B2 Fitness Tracker Bluetooth 4.0 Smart Bracelet, IP67 Waterproof, Support Sports Modes / Heart R worth to buy? Thanks for it if those of you who have purchased SMA-B2 Fitness Tracker Bluetooth 4.0 Smart Bracelet, IP67 Waterproof, Support Sports Modes / Heart R could share about what you think of the product. I would love any extra info, as it is quite pricey as $35.60 and I just want to know it is good before paying for it.