I inspected what are the real height of several optics, and what is the thickness of the underplate of IMMT1 suspension.

• The center points of STM1, STM2, and POM2 seem to be 210 mm from the top of the optical breadboard in IFI. (Figs. 1, 2, and 3)
• IFI seem to be ~220 mm. (Fig. 4)
• IMMT1 suspension sits on a thicker underplate; it is not two plates but one plate. The nominal thickness of the underplate is usually 10 mm, but this thick one would be 19.9~20 mm (Fig. 5).

May I will do the same with a laser level.