S2 Sport Smart Band Wrist Bracelet Wristband Heart Rate Monitor Fitness Tracker IP67 Waterproof Blue worth to buy? Thanks for it if those of you who have purchased S2 Sport Smart Band Wrist Bracelet Wristband Heart Rate Monitor Fitness Tracker IP67 Waterproof Blue could share about what you think of the product. I would love any extra info, as it is quite pricey as $29.90 and I just want to know it is good before paying for it.