those are syringe filters and vacuum filters. I am talking about FILTER NEEDLES. These are actual needles with a very tiny filter inside the plastic base. Something like a 19-gauge, 5µm filter needle, for drawing solutions from glass amps to filter out glass particle contaminants from the solution.
Those 0.45µm's are too expensive for this at $7.00 each, compared to about 0.40 cents for a filter needle. Not to mention the whatmans are overkill, since most particles are no smaller than 10µm.