against the surrounding introducer housing and also potentially with the housing of a medical connector used to deliver a medical implement through the introducer as seen in fig1 and 12 12 b the distal instrument sealing portion of the valve body 100 includes a pair of diametrically spaced axial side walls 110 a 110 b and a pair of duckbill walls 112 a 112 b therebetween the side walls 110 a 110 b are arcuate about the axis 106 and the walls 112 a 112 b are planar as in the first embodiment as seen in fig1 b the walls 112 a 112 b define an exterior included taper having an angle u03b2 1 that is larger than the included internal taper angle u03b2 2 such that the walls become thinner in the distal direction the walls 110 112 terminate at a common distal face 114 that is flat and in a radial plane an h shaped septum or slit opening 116 is formed in the distal face 114 and performs a sealing function in the absence of and about any instruments passed through the valve body 100 from the proximal to the distal ends the valve body 100 has a single reinforcing rib 118 a 118 b on each of the duckbill walls 112 a 112 b that meet at the slit opening 116 and are perpendicular to a middle segment of the h shaped opening the ribs 118 a 118 b project outward from both the respective duckbill walls 112 a 112 b and.