You must have at least one set of BLE Nano Kit v2 because you will need the companion board, DAPLink v1.5 board, which is used to load firmware into BLE Nano 2 from a PC.
BLE Nano 2 is the smallest Bluetooth Low Energy System-on-Chip (SoC) development board, only 18.5 x 21mm. You could develop application using Nordic's SDK, mbed.org or our open source Arduino Library for nRF5x.
For product introduction, please refer to our Kickstarter page for more information.
Getting started guide and technical details on our GitHub page.
https://github.com/redbear/nRF5x