The present invention provides sintered porous plastic plugs for use in filtered serological pipettes which facilitate manufacture or assembly of the filtered serological pipettes. In one embodiment, a sintered porous plastic plug of the present invention comprises plastic and a cylindrical body, a first end and a second end, the first end having a cross-sectional area less than the cross-sectional area of the cylindrical body, and the second end having a cross-sectional area less than the cross-sectional area of the cylindrical body.