1928 No. 7 set in a red box
Erector author Bill Bean seems to say that this set does not exist. He says, in his book "Greenberg's Guide to Gilbert Erector Sets Volume One 1913 - 1932", that all the 1928 sets except the No 7 and the No 10 came in red boxes; and that the No 7 set came in a stained wood box. However, here is a red box No 7 set from 1928. And California dealer and collector Paul Jennings has told me that he has one also. The set might have been shipped in 1929 (I don't have the manual to decide) but the normal 1929 No 7 sets came in a larger red box. Notice the 7 stenciled on the lower right corner of the lid.