Do these use proprietary brake pads that are only available from you, or are replacements available from a local auto parts store?

• What does the back of the USB socket look like? Can it be wired to a stereo that supports USB inputs so you can charge install
• Do you need to change the Is proportioning valve if I have disc in front? general
• Do I still use the spacer if I use your heavy duty axle retaining plate? The instructions appear to depict using the sp install