Developing and Testing Health Warning Labels on the ENDS Device

Inclusion Criteria: * Generally healthy individuals (determined by physical examination). * Age of 21-35 years. * Is willing to provide informed consent. * Is willing to attend the lab as required by the study protocol. * ENDS users (defined as using ENDS either daily or occasionally in the past 30 days) * Have abstained from ENDS use for 12 hours prior to each session. Exclusion Criteria: * Report smoking cigarettes regularly (\> 5 cigarettes/month in the past year). * Report regular use of any other tobacco/nicotine product (e.g., e-cig, pipes, cigars) in the past year. * Women who are breast-feeding or test positive for pregnancy (by urinalysis at screening). * Individuals with self-reported history of chronic disease or psychiatric conditions. * Individuals with history of or active cardiovascular disease, low or high blood pressure, seizures, and regular use of prescription medications (other than vitamins or birth control). * Individuals that report the use of non-commercial (i.e., street) e-cigarette liquid or products * Individuals that report current EVALI or COVID-19 related symptoms (i.e., cough, shortness of breath, chest pain, nausea, vomiting, abdominal pain, diarrhea, fever, chills, or weight loss) * Individuals that have or have been exposed to COVID-19 in the last 14 days.