Inclusion Criteria:  Current daily cigarette smoker as determined by:  a. Smokes >5 cigarettes/day for >1 year  Willingness to abstain from using cigarettes for 8-10 hours (overnight abstinence) prior to study visits (verified by exhaled-air carbon monoxide < 10ppm). Self-report fair or better physical health. Self-report fair or better mental health. Participant must understand the investigational nature of this study and sign an Independent Ethics Committee/Institutional Review Board approved written informed consent  Exclusion Criteria:  Currently uses other tobacco or nicotine products (e.g., smokeless tobacco, ENDS) > 2 days/week. Self-report having active, untreated medical/psychiatric conditions History of serious side effects from nicotine or from any nicotine replacement therapies. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. Nursing female participants. Vulnerable populations, such as cognitively impaired adults, individuals who are not yet adults, pregnant women, and prisoners. Unwilling or unable to follow protocol requirements. Any condition which in the Investigator's opinion deems the participant an unsuitable candidate to receive study drug. Previous use of either of the study products (ZYN or Vuse Alto).