The Carrier Card is an add-on for use with the Carrier Board, via which it connects to up to 19 I/O pins on a JeeNode or SMD Kit. The entire inner area is perforated with plated-through holes, to allow mounting a variety of components.
The Carrier Card is split in two sections which can easily be broken apart for independent use. There are GND and VCC grids along the short edges of the board. The top of the board has holes for up to five 6-pin headers, clearly labeled to match the signals coming from the Carrier Board.
The PCB only version contains just the Carrier Card.
The 5-pack offers a buy-5-for-the-price-of-4 discount option.
The documentation and full design details are fully available.