This is an internal filter wheel for the ST-402ME only. It contains very high quality interference filters custom made for this camera. Note that the filters are permanently attached to the filter carousel and cannot be changed.
Also, due to the size of the CCDs, the internal filters will not cover the KAF-1603ME or KAF-3200EM CCDs in this camera body. Therefore, for the larger ST-1603ME and ST-3200ME cameras, the external CFW10 filter wheel with 1.25" filters must be used.