A sheath can include a sheath body and a sheath hub. The sheath body can have a generally flexible tubular structure, a proximal end, and a distal end. The sheath body can further define a longitudinal axis. The sheath hub can attach to the proximal end of the sheath body and define a longitudinal axis generally aligned with the axis of the sheath body. The sheath body and sheath hub can also form a central cavity along their respective axes. The sheath hub can include two plates: a flexible plate and a rigid plate. The rigid plate can have a relief generally centered on the sheath body's axis. Advantageously, the flexible plate and rigid plate can overlap to substantially seal the central cavity.