Convenience of a bottle top filter with the ability to re-use the filter housing Nalgene 320 Autoclavable Securely screws onto glass media bottles* with 33 mm or 45 mm neck sizes Deep screw threads attach directly to bottle allowing convenient filling and vacuum filtration without holding filter to bottle Major components molded of durable, break-resistant, transparent polysulfone (PSF), which is non-toxic, easy-to-clean and exhibits low protein-binding Removable sterilization membrane support plate provides maximum flow rate and throughput Molded-in graduations Cover ports accommodate 1/4” i.d. tubing for flushing procedures, sterile venting or pressure filtration Without required membrane, accepts 47 or 50 mm membrane * Use only sterile bottles designed for use with a vacuum