The signal strength of your phone is measured in dB’s with values appearing as negative numbers. The lower the negative dB rating, the better the signal strength. The scale is logaritmic so the change in dB means more than just the raw value. Antenna79, the makers of the ReachCase, advertise that you can see up to a three times improvement in signal strength.
Looking just at the bars on your phone doesn’t give you an accurate measurement of signal strength and you may not see any change in those bars with the ReachCase. A three times improvement in signal strength can be indicated by five dB. On some phones, it could take up to a 10 dB improvement to change a bar on your phone status line, which is a 10x improvement in signal strength.
So, you are not likely to pop on the ReachCase and see three more bars magically appear on your phone or see massive changes in dB levels. In my testing in various areas, I saw consistent improvements of two to five dB when extending the ReachCase back slider down. ReachCase has been tested by independent third party labs and has shown to increase LTE signal strength up to three times.