Same form factor as a Pi HAT. Uses I2C pins for communication with Notecard. This Notecarrier can communicate with a Notecard (larger form factor only) via AUX serial, enabled with a DIP switch. The usual carrier DIP selects 1.8V or 3.3V operation. Passthrough cutouts for camera + display FFC's from the Pi underneath. Micro USB port for developers. External SIM slot available.