Inclusion Criteria:  Females:  Aged 18-30 years old, inclusive, at Screening based on self-report Sexually active, defined as having had penile-vaginal sex with a male partner at least four times per month (e.g. once a week), on average, in the three months before Screening In a mutually monogamous relationship with the same male partner for at least 6 months prior to Screening, based on self-report Male partner is eligible and consents to participation Healthy based on medical history and physical exam at Screening Currently using effective non-vaginal contraception for at least 3 months prior to screening, including injectable, oral contraception, contraceptive patch or sterilization (male or female) based on self-report HIV-negative per test at Screening Not pregnant per urine pregnancy test at Screening and Enrollment Negative for chlamydia, gonorrhea, trichomoniasis or urinary tract infection (UTI) at screening Symptomatic vulvovaginal candidiasis or bacterial vaginosis (BV) at Screening. (Participants who test positive at initial screening may be treated and rescreened after completing treatment). Competent to provide written informed consent based on Investigator's assessment Owns or has access to Smart phone per self-report Agrees to not participate in any other clinical research for the duration of this trial  Males:  Aged at least 18 years old at Screening based on self-report Sexually active, defined as having had penile-vaginal sex with a female partner at least four times per month (e.g. once a week), on average, in the three months before Screening In a mutually monogamous relationship with the same female partner for at least 6 months prior to Screening, based on self-report Female partner is eligible and consents to participation Healthy based on medical history and physical exam, including visual inspection of genitalia at Screening HIV-negative per test at Screening Negative for chlamydia, gonorrhea, trichomoniasis per tests at Screening (per local standard of care) at Screening Competent to provide written informed consent based on investigator's assessment Owns or has access to a Smart phone, per self-report Agrees to not participate in any other clinical research for the duration of this trial  Exclusion Criteria:  Females:  Known or suspected allergy to silicone, as reported by participant Positive pregnancy test at Screening or Enrollment based on urine hCG test Positive for HIV per test at Screening Presence of any clinically significant genital epithelial findings (e.g. abrasions, ulcerations, lacerations, or vesicles) suspicious of STIs at Screening or Enrollment Positive chlamydia, gonorrhea, or trichomoniasis test at Screening (or Enrollment) Current urinary complaints or diagnosed UTI at Screening (or Enrollment) Presence of genital abnormalities via visual exam with speculum that would contraindicate IVR use at Screening or Enrollment Significant uterine or vaginal prolapse, or urethral obstruction Recurrent vaginitis (three or more episodes within the prior year) Unexplained vaginal bleeding per self-report within the 3 months before Screening Currently breastfeeding per self-report Partial or complete hysterectomy per self-report Gynecological surgery in the 6 months prior to Screening per self-report Within 6 weeks post abortion or 6 months postpartum, per Self-report. Using vaginal contraception (diaphragm, female condom, spermicide, IVR) Use of an intrauterine device (IUD or IUS) Abnormal finding on examination or a social or medical condition which, in the opinion of the investigator, would make participation in the study unsafe or would complicate interpretation of data. Any other condition the clinician feels would jeopardize the health and wellbeing of the participant after assessing the participant's potential eligibility for the study Unable to comply with study requirements, including but not limited to, attending all study visits and using the IVRs as directed. Currently participating in any other clinical research trial involving investigational or marketed products  Males:  Known or suspected allergy to silicone, as reported by Positive test for HIV at Screening