How to use a durst Femka neg carrier?

Hi,

I bought a durst 1200 enlarger with condensor head and along with a lot of other stuff there was a negative carrier mentioned durst femka 4x5.

Has anyone heard of this? I can not get any info from google about it.

If I have time i can make a pic of it.
I am not going to use it, but would like to know what it is.