I loved the European FL2 app, USA version awful. 1: My phone is in a band on top of the sensor, almost hourly I get an alarm 'lost signal with sensor'. 2: It's phone or reader. In europe i would activate the sensor with my phone and could also use the reader. 3: if phone's battery life goes below 70% it struggles to read the sensor. 4: NFC reading is buggy, rarely successful reading on 1st, 2nd or 3rd try. 5: high/low alarms not timely and often out of range (low set at 80, alarm goes off at 67)