Are wanting to know how to use the heart rate monitor on your phone? And do you need advice on finding a case that will fit the phone?
If you want something free for your heart rate monitor you can download this app
As for cases there are literally hundreds to choose from, you just need to make sure that it fits the 6s before you buy it, it will usually say. Cases can range in price from under $10 to $50 or more. Usually you get what you pay for.
There isn't a connection between the case and heart rate monitor. To monitor heart rate with the phone you just need to download that free app I linked you all though there are other ways as well.
The easiest way to make sure you do not make any mistakes is to get the case at the store instead of online. Go to your local apple store and if you do not have one of those either go to best buy or walmart which both have a large selection of cases.
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