28415314. PTFE Membrane, TE Range (TE 36), 0.45 µm pore size, 25 mm circle (50 pcs) 28415315. PTFE Membrane, TE Range (TE 36), 0.45 µm pore size, 47 mm circle (50 pcs) 28415316. PTFE Membrane, TE Range (TE 36), 0.45 µm pore size, 50 mm circle (50 pcs) 28415308.