Non-catalytic component of the exosome, which is a complex involved in RNA degradation. Increases the RNA binding and the efficiency of RNA degradation. Helpful for the interaction of the exosome with A-poor RNAs (Probable). Component of the archaeal exosome complex. Forms a trimer of Rrp4 and/or Csl4 subunits. The trimer associates with a hexameric ring-like arrangement composed of 3 Rrp41-Rrp42 heterodimers. Interacts with DnaG (Probable). Contains an N-terminal domain that mediates interactions with the hexameric ring, a central S1 domain and a C-terminal zinc-ribbon domain. The zinc ion has probably a structural role. Belongs to the CSL4 family.