A protein complex required for clamping microtubule binding sites, ensuring orientation of sister kinetochores to the same pole (mono-orientation) during meiosis I. In the yeast S. cerevisiae this complex consists of Csm1p, Lrs4p, Hrr25p and Mam1p; in S. pombe Psc1 and Mde4 have been identified as subunits.