It only supports non framed filters, I missed that detail so I am unable to use the holder with regular framed filters as intended.
It is a good filter drawer, but so thin I had to unmount my CLS-CCD filter to put it in. The adapters that come with it are extremely difficult to remove (I want to make it M42 female on both sides with an M52-M42 ring, but I am unable to remove the current adapters).