An accessory called Multi-Kilar acts like a zoom Macro lens attachment.
Is made to only work with the Marco-Kilar 90mm f/2.8 lens There
is a lens inside the tube that matches with the 90mm Macro-Kilar
lens. Up by the front of the Multi-Kilar is focusing helical that
is marked x2, x21/2, x3, x31/2 and x4 went it is turned the magnification
changes from 2x to 4x or power. The on the right side of the lens
is a hand crank that you turn like a variable extension tube, it
is marked x2-x4 to match up with magnification that you selected.
There are three different tripod mounts on the bottom of the lens
as well as a built-in drop-in filter slot. For more information
50 Jahre anders als andere", by Lothar Thewes, page 111