Takahashi Adapter TKP86005 from M54x0.75 to M43x0.75 (# 12).
Used on the FSQ-85ED, FSQ-106ED and CCA-250, but also on the FC-100DF and FC-100DL when the 0.66x Reducer also wants to be used visually.
On the eyepiece side Coupling S (TKP00103) or Coup