Although the BAC-601 Display unit provides a digital speedometer, it does not allow you to modify any of the controller parameters during a trip like the Bluetooth application does.
The biggest problem I find with the BAC-601 Display unit is that it does not retain any of the trip data when the battery is turned off, the odometer is the only information that isn't lost.
![](http://www.arhservices.co.uk/GoldenMotor/MP4/PA032431_zpsed18150e.JPG)
![](http://www.arhservices.co.uk/GoldenMotor/Bluetooth%20app/2015-12-24%2020.36.02_zps3ysmzaf0.PNG)
If you are using a pedelec sensor, the separate mode selection button unit that comes with the BAC-601 is probably easier and more convenient to use by feel alone instead of having to look to see exactly where to press on a phone display.
Because the BAC-601 Display unit and mode selection switch is permanently fitted to the bike, you will never set off on a trip without it. Whereas with the Bluetooth option, if you go for a ride without your phone, you will not be able to adjust the level of pedelec assistance or log any details of the trip.
Alan