The filters do fit perfect...They are just very easy to come off (just by shaking the filter holder with the glass filter in it will cause it to fall. I have a Chrosziel matte and the filter tray holds the filter VERY well(tight). You can not get them out unless you pull the release mechanism. It's just up to the user...if you are extremely careful all the time, you will be OK. NOT and ideal solution for me: if you forget, the filter can be on the floor in no time...
If you are planning to use it a lot, I would personally suggest something better built (Red Rock MIcro, Cavision, Indifocus is coming out with something interesting real soon...)

Carlo Zanella
The Santa Fe TV Show