The nRF51822-4 module is small, and so this is a small breakout board to go with it. It adds an LED, which is controlled by pin P0.09. It provides through-hole pads for 5 of the unused pins and provides SMD pads for the remaining two unused pins.
This breakout board measures 11.40mmx16.71mm. As you can see from the photo, the fully assembled board is not much larger than a dime.
For ease of programming, the board includes a 10-pin IDC connector.
To receive serial output from the module, you can use use this adapter: https://www.openhardware.io/view/484/IDC-10-pin-ARM-debug-adapter