Inclusion Criteria:  Able to read, understand, and willing to sign an informed consent form (ICF) and complete questionnaires written in English. Generally healthy male or female adults, ≥ 21 years of age, inclusive, at the time of consent. Positive urine cotinine test at the Screening Visit. Non-cylindrical, cartridge-based, closed-system ENDS are the primary form of tobacco- or nicotine-containing products used within 30 days of the Screening Visit. Subjects may be users of other tobacco- or nicotine-containing products. If the subject is a dual/poly user of tobacco- or /nicotine-containing products then the subject must self-report that a non-cylindrical, cartridge-based, closed-system ENDS is their primary product. Must have used 2 or more cartridges per week over the last 30 days. Brief periods of abstinence due to illness, quit attempt (prior to 30 days of the Screening Visit), or clinical study participation (prior to 30 days of the Screening Visit) will be allowed at the discretion of the Principal Investigator (PI). Females must be willing to use a form of contraception acceptable to the PI from the time of signing the ICF until the end of the study. Must be willing to use the assigned IP and only the assigned flavor as their exclusive source of ENDS use for the full duration of the 9-day ambulatory period. Use of other non-ENDS tobacco- or nicotine-containing products will be permitted during the ambulatory period. Must have familiarity with modern electronic devices such as an IOS/Android smart phone or tablet computer ("tablet") and be willing to be provided with an electronic device, that allows for both Bluetooth connectivity and internet connectivity. Must be willing to use an application on the electronic device and keep the application active for the length of the study Able to safely perform the required study procedures, as determined by the PI.  Exclusion Criteria:  Presence of clinically significant uncontrolled cardiovascular, pulmonary, renal, hepatic, endocrine, gastrointestinal, psychiatric, hematological, neurological disease, or any other concurrent disease or medical condition that, in the opinion of the PI, makes the study subject unsuitable to participate in this clinical study. History of or presence of diabetes. Systolic blood pressure of > 160 mmHg or a diastolic blood pressure of > 95 mmHg, measured after being seated for five minutes, with exceptions at the PI's discretion. Scheduled treatment for asthma currently or within the past consecutive 12 months prior to the Screening Visit. As-needed treatment, such as inhalers, may be included at the PI's discretion pending approval from the Medical Monitor. Any history of cancer, except for primary cancers of skin such as localized basal cell/squamous cell carcinoma that has been surgically and/or cryogenically removed. Use of any medication or substance that aids in smoking cessation, including but not limited to any nicotine replacement therapy (NRT, e.g., nicotine gum, lozenge, patch), varenicline (Chantix®), bupropion (Wellbutrin®, Zyban®), or lobelia extract within (≤) 30 days prior to the signing the ICF. Participation in another clinical trial within (≤) 30 days prior to signing the ICF unless allowed at the discretion of the Principal Investigator (PI). The 30-day window for each subject will be derived from the date of the last study event in the previous study to the time of signing the ICF in the current study. Females who have a positive pregnancy test, or who are pregnant, are breastfeeding, or intend to become pregnant during the course of the study. Individuals ≥ 35 years of age currently using systemic, estrogen-containing contraception or hormone replacement therapy. A positive urine drug screen without evidence of prescribed corresponding concomitant medication(s) at the Screening or Enrollment Visits. Postpones a decision to quit using tobacco- or nicotine-containing products in order to participate in this study or a previous attempt within (≤) 30 days prior to signing the ICF. Drinks more than 21 servings of alcoholic beverages per week or has a positive test for alcohol result at the Screening or Enrollment Visits. Employed by a tobacco- or nicotine-manufacturing company, the study site, or handles tobacco- or nicotine-containing products as part of their job. Determined by the PI to be inappropriate for this study.