FG-7 is said to be based on Champlin #16. This has some credence since Edmund Lowe the founder of Edwal said that this was the only developer in Champlin's book that was worth anything. Another supporting fact is that both developers used chlorhydroquinone. The bad news is that this developing agent is no longer available. For a period of time Edwal has synthesized this chemical when it was no longer available. Before anyone asks the synthesis is NOT something you want to do at home. It requires two dangerous chemicals.