The Blink Plug is a small board with room for two LEDs and two push buttons. A simple software trick can be used to interface to both switches and LEDs using only two I/O pins.
The Kit variant includes the PCB, a red and a green LED, resistors, and pushbuttons.
The PCB-only variant contains just the board for the Blink Plug. No parts, no headers.
As connectors you can use a Plug Headers set with 10 male and 10 female 6-pin headers, which makes it easy to connect multiple plugs and JeeNodes in a “standard” way. Or you can solder the board directly in place for more permanent use.
The documentation and full design details are freely available.