New revo project rig Tqi 5 channel reciever?
 

What are all 5 channels for

The 1st 2 are obvious(steering and throttle/brakes). The 3rd is typically used for shifting(if you have 2 speed electric, for example, or shifting to reverse for the nitro truck). The summit also has a diff lock feature(another channel). "Extra" channels can be used for various things, such as a fan for the motor, lights, etc. :-)