Hi Colin, Hi Ryan.

If you have a dual channel esc (one like the sabertooth, scorpion or ragebridge) that has two outputs then you only need the one. The Botbitz are single channel, each one only controls a single motor so you will need two.

Failsafe is not really an additional component (although it can be) It just means that when your transmitter is turned off your robot stops moving. In order to enter a competition you will have to pass a tech check where among other things you will have to put your robot into full forward and switch off your transmitter, if the robot's motors stop turning you pass and if not then you haven't failsafed and will fail the tech check. You can normally set this by getting decent radio gear and rebinding the transmitter and receiver with your settings and trims in neutral.

Harry.