The NDC-PM Post Mount Assembly allows you to mount any of our round, unmounted, continuously variable (or step) ND filters onto a rotating axel that can be threaded onto any Thorlabs Ø1/2" TR Series Post. Simply unscrew the thumbscrew on the side with 3 washers, remove two of the washers, insert the filter wheel, place the two washers back on the thumbscrew threading, and re-thread the axel while the other two (one on each side) are used to ensure smooth turning motion. The two thumbscrews thread into a special 0.75" long ER rod. Whose position can be translated using the included 0.050" allen key. If a longer distance is needed between the post and the filter wheel, you could simply swap out the included 0.75" long ER rod for any other standard length. The mount has a minimal effect on the clear aperture of the ND filter. Adapters for both 8-32 and M4 mounting holes are included with each mount.