Lee foundation kit
there should be about 2-4 "slots" that can hold the ND filters. You have to add/screw on the additional side pieces that form the "slots" for the filter(s) to slide into, or add the pieces that make the slots wide enough for the filters. The Filter holder is NOT designed to hold gelatin filters, (the soft, very thin ones that flex when you hold them by the edges. ) only resin or glass filters, such as those made by Calumet, Sinar, Lee, etc. Also, you'll need to experiment a little with the tension of the screws to allow the filters to fit.
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