It works - generates a bit of heat, but it works.  Will gain 1-4 bars depending on how bad the signal is.  Key is getting a good antenna OUTSIDE your vehicle, house or RV.  Many to choose from, just make sure the connector is right for this device (buy an adapter if needed.)  I use with AT&T LTE and Sprint LTE.  Device gets 3 more bars when placed in this cradle.