This is the JR Sport Standard 6-Inch Y-Harness. These are required to run two servos off of one receiver port. These are often used to run aileron servos.
This is the Traxxas BEC Y-Harness. This is allows for the use of a BEC, while still running accessory items like LED lights off the ESC auxiliary power wire.
The Y-harness has two female JST...
This is the JR Sport Standard Switch Harness. These have the separate chargewire so there is no need to unplug the battery from the switch lead to charge it like with the cheaper switches.