This 500mL Rapid-Flow™ series 295 bottletop filter unit consists of a polystyrene housing and a 75mm/0.45µm polyethersulfone (PES) membrane filter. The sterile disposable tissue culture filter unit securely screws onto media bottles with 33mm neck sizes. Allows vacuum filtration of liquid directly into sterile bottles. CAUTION: Use only sterile bottles designed for use with vacuum. Always use safety shield during vacuum procedures. This product is not intended for use in direct patient care or diagnostic procedures. Features molded-in graduations and a side-arm with quick-disconnect tubing adapter. Blue collar. Material: polystyrene housing and a PES membrane. Capacity: 500mL. Membrane diameter: 75mm. Pore size: 0.45µm. Bottle neck size: 33mm. 12/Case. Nalgene®#: 295-3345.