Precision Works Throttle Body Adapter K2B B2K K2H K-Series H-SeriesPrecision Works Throttle Body Adapter K2B B2K K2H K Series H Series Installing a B Series throttle body onto a RBC K Series? This is the adapter you need! This PLM throttle body adapter is for fitting a B Series throttle body on a K Series RBC or RRC manifold or similar flanges, also known as K2B or B2K. Many H Series engines now also use an adapter plate to run K Series RBC Manifolds. This is the perfect flange to run H Series throttle body on K