Update: This is going back and we won't be ordering the V19Pro as planned as a result.While step & heart rate tracking is fine, everything else seems completely made up.My BP numbers are oddly cocsistent... just not consistent with my real readings.But I largely got this for sleep and O2 tracking. And this is garbage for those.The O2 reading stays at a flat 98%, which isn't accurate or normal. For someone monitoring sleep apnea oxygen levels, this could be dangerous.And sleep tracking is a joke. If you know how sleep cycles work, you know deep sleep most often comes early with REM mostly coming later. I've used other, more accurate, sleep trackers and they get this right. This band just churns out erratic readings all night (see screenshot), & shows no awake time ever even though I wake up multiple times per night. Garbage data.I've also had a lot of trouble with the band's Bluetooth. It can go half a day without syncing to the app for me to review my data. If a fitness band can't consistently feed you data, what's the point?It feels like the bare basics work, but all the other features are just for show, feeding you BS "data" so it appears to be doing things it's not. Not OK.---Original review:I picked this band because the company page on Amazon specifically said it was the latest HRV tracker. But it's not. If you go to their own website, there's a newer version (the v19Pro) that's slightly larger and that adds ecg/ekg and glucose tracking (though supposedly the latter is disabled for US users). And while that's listed as a "new" item there, I'm seeing references to it being available elsewhere for at least a year. They're not yet making that version available here on Amazon. But they shouldn't be advertising this here as the latest version when it's not.For the actual band:1. It takes a little while to get used to, but it's not the worst setup I've seen.2. The heart rate and step trackers were extremely accurate -- down to the exact step count in my testing, and almost always an exact match to hear rate measurements on my Galaxy Watch 5, blood pressure machine, and SP02 fingertip tracker.3. BP measurements aren't something to rely on if you have heart issues, but initial testing shows it's "close enough" for more general reference to let you know if you're way out of the norm. Compared to both a dedicated blood pressure machine and my Galaxy Watch 5 (which was more accurate), the diastolic (lower) number is usually within a point or two, but the systolic (upper) number can be more like a 5-10 point variation. All that said, we tried BP tracking with this on two people and the results are very similar. That's odd with one tester having high blood pressure and the other not. So the initial accuracy testing could have been a fluke.4. We just did the first night's sleep tracking test, and it was terrible. It showed no awake time which wasn't true at all. It also didn't detect sleep apnea even when a partner was there to physically observe it multiple times. It tracked my oxygen at a flat 98% all night with no fluctuation (not possible when you literally stop breathing for stretches). And it showed me wildly jumping between light, deep, and REM sleep all night at brief erratic intervals, which simply isn't how sleep works (and again, it missed every "awake" period). We've tested other sleep trackers, and none of them was this far off. The sleep tracking was a major reason for the purchase, specifically to track oxygen while sleeping because the Galaxy watch slips too much during sleep to get accurate O2 readings. We'll try it a couple more nights, but if this shoddy reporting continues it's going to be completely unusable for my needs.5. The app is... not great. There are syncing issues. When you open it, you won't find the latest data often. You need to swipe to sync. Then you'll get some data, but it's not always complete. I sometimes have to swipe to sync 2-3 times over the course of a few seconds before all tracked readings actually show up in the app. This isn't particularly helpful.Overall, disappointed the newer model isn't here (we highly prefer ordering through Amazon in case there are any issues). And while this does a fine job for heart rate and step count, that's not why I ordered it, and if readings continue to be so far off, it might have to get returned.