The pharmacokinetics of a microbicide gel, i.e. the time- and space-dependent distribution of its active microbicidal ingredient(s) (APIs) throughout the body, derives from the time- and space-dependent distribution of the gel itself within the vaginal canal. That distribution may also serve as a physical barrier that retards migration of semen-borne HIV virions to epithelial surfaces. Within the vagina, the gel creates local physical forces ("stresses") against the epithelial surfaces; and its distribution along the canal might be so extensive that gel leaks out from the introitus. A woman may have sensations of those stresses and also feel gel leakage. Thus, intravaginal microbicide gel distribution is central to both its biological functioning (to deliver APIs and also to slow HIV transport) and the behavioral perception of it by users (i.e. how it "feels" and whether that experience is pleasurable or not). The latter, in turn, can govern acceptability of the gel and adherence to designated gel use in clinical trials. This study will characterize and correlate gel distribution and women's sensory perceptions and preferences of that distribution, for two relevant volumes (2 mL and 4 mL) of a current microbicide placebo gel. An optical vaginal imaging device will measure gel distribution in the vagina. A computer-assisted self-interview (CASI) survey will capture women's perceptions and preferences.