The one I posted has:
RCA pre-amp outputs so you can drive an external amp for a subwoofer. Also has the trigger line for the amp.
USB port that can be used as an audio source and also charges devices. I ran a 6 foot USB cable off this under the carpet for my phone but I just got a center console and will replace that cable with a port hidden inside the console.
Aux In 3.5mm jack
RCA Pre-amp inputs
The remote has power on/off, source, volume, advance/repeat/pause on a corded and illuminated remote that I hid in the glove box. Never really touch it though since I control everything from the phone
This photo shows where it sits inside the dash. I used velcro to hold it on top of the AM radio. I ran a relay to use the original radio power as trigger and power the device from a new fuse box inside the dash that has direct power from the battery. This is necessary because it had higher rated fuse than original, I also used that new box for the new AC system.
I now have a battery drain. Pretty sure it is radio because it has an always on source and the ignition trigger (I think this trigger is a relay so I probably double relayed it.) I don't need the always hot line unless it is going to forget the bluetooth pairing without it. I don't think it does though.