Hi Darrell
Most top line filters come unmounted for serious CCD work, this reduces the vignetting providing maximum filter aperture.
There are a number of filter wheels (or seperate internal wheels) available that accept unmounted filters. The filterwheel of choice for 50mm filters is deffinitely the FLI CFW-2-7 and I highly recommend it, it is really the industry standard 50mm FW. The FW comes with thin retaining rings that hold the filters in the filter pockets.
Remember also that FLI offer the narrowband set as well so you could upgrade to the whole imaging set if you wished
Cheers
Mike