Like many others, I purchased this because it was advertised as compatible with Apples HealthKit and Health app. And, like many others one of the first things I did was to enable "integrate with Apple Health" in this apps settings. Which, it turns out, is why like many others, the app did little more than lock-up each time it tried to communicate with Apples Health app.
Folks, this may be a fine device, but without the ability to combine (aggregate) its results in one place along with data from multiple other sources, its just a BP cuff and an overpriced one at that. They are very impressed with their own app (which they believe is "good enough" for anyone), but just dont get it when it comes to Apples HealthKit. So unless and until they figure this out, DONT BUY ANYTHING WITH THE QARDIO BRAND. There are better and less expensive alternatives if you dont care about HealthKit.
NOTE: This issue is only the beginning of problems with this product and this vendor. It is surprising that Apple would endorse the product on its website. For instance, apparently there is no easy
way to share the device on more than a single iPhone (so my wife cannot also use the device and track her results over time). Add to this the lip-service-only that serves as Customer Service (they offer only eMail support, and ignore you following their first "canned" reply). Do yourself a favor and avoid this device and its vendor.
DrBilly about Qardio heart health, v1.60.1