Whatman Whatman 10463413 10463413 PTFE Uniflo Membrane, 25mm Diameter, 0.2 Micron (Pack of 1000) Sale price. $1,141.81. Add to cart. Quick view. Whatman Whatman 10463422 Uniflo 25 Syringe Filter with 0.45 micrometer PTFE Membrane, 25mm Diameter (Pack of 500) Sale price. $648.57. Add to cart.