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There are transmittance vs wavelength curves around for both types of filters. Sorry, don't know where exactly, but I've checked them out before (just google). I believe the Sirius ones are not as selective, and peak transmittances are not as high; i.e. they look like cheap imitations of more expensive low/high/band-pass filters. I should emphasise that this is solely from looking at the manufacturers' data (which can of course be fudged), not through the eyepiece.
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