The Conversion Boost Controller (BC-CBC) let you turn your single stage Standard Boost Controller (BC-SBC) into a Dual Stage Boost Controller.

Picture is of a Dual Stage Boost Controller (BC-DSBC) not a Conversion Boost Controller (BC-CBC). This is what the end result will look like after assembling the Conversion Boost Controller (BC-CBC) to the Standard Boost Controller (BC-SBC).