"The Geiger Kit is a board that provides the electronics needed to run, and detect events from the GM tube, along with a microprocessor (ATmega328) that makes it easy to customize a solution for processing and outputting the events. Both the Geiger circuit and the processor can be used independently of each other if desired.
What's in the Kit:
The basic kit (KIT-A) consists of the printed circuit board (PCB) and all of it's components (about 60 pieces) with the exception that the ATmega328 is only included in KIT-B. Assembly requires moderately good soldering skills, but care should be taken that the right part is being soldered in the right way. The lead clearance is pretty tight and parts are difficult to desolder if they are put in wrong."