Showing slide 1 of 7 - Best selling. Go to previous slide - Best selling. 5 off 0.45um 25mm Syringe Filters Whatman Gd/x PTFE 6874-2504 Filtration Lab. £6.45 New. 33mm Millipore Millex Sterile Syringe Driven Filter 0.45µm PES Membrane X 50. £14.11 New.