Sorry for dumb question. I have bought a Kardia mobile and have an iPhone 6s. Should I attach it to my phone? What do people find is the best way to use this? I don't want the Kardia to be damaged, also not sure what type of phone case I can then use to protect my phone. Currently I have a flip down cover which protects front and back of the phone. Do some people keep the Kardia separate in its own case?