Non-catalytic component of the exosome, which is a complex involved in RNA degradation. Increases the RNA binding and the efficiency of RNA degradation. Confers strong poly(A) specificity to the exosome. 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. Belongs to the RRP4 family.