(A) A LR-SCT, SCT locking-ring is directly screwed onto the SCT back. The Custom-Wheel is screwed on behind it and locked in position at the required angle. A focal reducer (in this case f/3.3) is screwed behind the Custom-Wheel using a (B) A SCTM-SCTM low-profile adapter. The extension tubes of the f/3.3 reducer can be directly screwed into the faceplate of a SBIG, LISAA or other CCD camera with a T-thread faceplate, of via a (C) A M42 T-Ring to a SX or other CCD camera with a 'Pentax' threaded (M42 x 1.0) faceplate.