One of the multiple factors required for polyadenylation and 3'-end cleavage of mammalian pre-mRNAs. Homodimer. The CSTF complex is composed of CSTF1 (50 kDa subunit), CSTF2 (64 kDa subunit) and CSTF3 (77 kDa subunit). CSTF3 directly interacts with CSTF1 and CSTF2. Interacts with FIP1L1.