Presumably a reissue on Hänssler of the set originally released by Thorofon:
https://www.jpc.de/jpcng/classic/detail/-/art/josef-rheinberger-kammermusik/hnum/12284425
As I remember, one or two of the works recorded in this series are dry, academic stuff, but many others are generously melodic and attractive works which are well worth exploring.
And at 6CDs for EUR19.99, an unmissable bargain...