How about Grandmaster Repertoire?

New in Chess is selling about 20 books in the Quality Chess GM Repetoire series. Are you talking about all of them? Just one?

Here is a review by Jeremy Silman of one of them- http://dev.jeremysilman.com/shop/pc/Grandmaster-Repertoire-1-d4-Volume-One-p3541.htm

Silman says:

One last and very important point is to consider your playing strength when considering whether to buy either or both of these books. They are principally aimed at players over 2200 on up (no limit!). Players from 2000-2200 will definitely have their hand full whether it is trying to learn to play the many types of middle game positions that offer White small advantages that Avrukh recommends or the main line theory of Bg5 against the Semi-Slav or 5.a4 Bf5 6.Ne5 lines in the Slav advocated by Schandorff. Those below Expert level should concentrate on improving their overall game before taking on such demanding material.

Both books are highly recommended. I give them my strongest recommendation.