I don’t think EMF-blocking phone cases are a great solution for reducing EMF exposure from cell phones. If you block all EMFs originating from a cell phone, the device won’t be able to maintain a cellular, Bluetooth or Wi-Fi connection. I think the better approach is to use wired headphones to be able to keep the phone away from your body while making phone calls. That means not having the phone in your pants pocket while making calls, as it might cause tissue heating in areas you don’t want heated.