littleBits Hardware Development Kit (HDK) is the quickest way to get started developing your own module for the bitLab. The two proto modules allow you to connect to PCBs and breadboards, while the perf module allows you to build a small circuit right on the module. When you're ready to design your own PCB, you can use the included gray bitSnap connectors to attach to the board. We've also included color-coded stickers so you can easily denote your bitSnaps as power, input, wire, or output.