So, this item shows up on the gear table on page 47 of Augmentation, and again in the compiled tables on page 170, but nowhere in the book can I find what it actually is.
Does anyone know? My first guess was that it was intended as a guide for converting other pieces of hardware into modular plug-ins, but it could also be for buying a secondary partial cyberlimb (or cyberhand/foot) to switch out with the normal one, or any number of other possibilities that I haven't thought of.