If you are looking for a Helo CFII study course I would wait for a newer version of the current CFII King course. The majority of the current course is outdated based on the new 2017 FAA changes for Instrument testing. However Kings School's customer service was great and made it right when I told them this current course did not meet my expectations based on the new FAA instruments written tests. However, I would order from them again as previous KS courses made getting other pilot ratings much easier for me.
Flight Instructor-Instrument (CFII) Ground School & Test Prep Course