For people who have completed part one, or already have experience making fragrances. More formulas and accords to practise, assignments, videos and the workbook - and you're getting the 65 material kit, professional perfumery materials diluted ready to use, with organic grain perfumers' alcohol.
The Extension online content: the videos and workbook. If you already have perfumery materials at hand, or you own the materials kit from The Essentials there's no need to order it again*.
(*Unless you've run out. In which case, you can buy sets of 5 materials at 4160Tuesdays.)