A valve assembly for use with a surgical instrument is disclosed. The valve assembly includes a housing and a seal assembly disposed within the housing, the seal assembly including a septum seal including an orifice configured to sealingly engage a surgical instrument inserted therethrough, at least a portion of the septum seal defining a seal curvature, a first guard member including a plurality of curved first guard portions defining slits therebetween, and a second guard member including a plurality of curved second guard portions defining slits therebetween. The first and second guard members may be positioned in an overlapping relationship with the plurality of first guard portions rotationally offset with respect to the second guard portions. The wide, triangular shaped slits of the guard members may improve flexibility of the guard portions.