The SQ-1 Y-Cable is a Futaba F-M-M Configuration that splits any Receiver channel into two connectors. The SQ-1 Y-Cable allows the SQ-1 to get power and signal off the Motor Port of your Receiver (normally Channel 2 on your Receiver). One leg of the SQ-1 Y-Cable is shorter than the other. Connect your Motor Servo to the short leg so they can both live inside your Receiver box. Plug your SQ-1 into the longer leg - this leg is meant to be run outside the Receiver box so you can easily connect and disconnect your SQ-1 and your vehicle.
The SQ-1 Y-Cable can be used with any device that you need to tap into power and signal from your Receiver.