Adaptive Use of Nicotine Substitution to Maintain Smoking Reduction/Abstinence in Nicotine Responders

Inclusion Criteria: * Healthy, adult smoker of combustible cigarettes. * Age 22 to 65 years at time of screening (verified by government issued ID). * Smoke cigarettes for ≥12 months prior to screening. * Currently smokes at least 10 tobacco cigarettes per day. * Screening eCO ≥ 10 ppm. * Voluntarily provides consent for participation by signing the informed consent form (ICF). * Willing and able to comply with study requirements. Exclusion Criteria: * Unable to read, speak or understand English * Has a history or presence of clinically significant medical or psychiatric disease, or any other condition that would in the PI's judgement jeopardize the safety of the participant, impair the participant's ability to comply with study procedures, or impact the validity of the study results. * Has used nicotine-containing e-cigarettes (or vapes) or any nicotine replacement therapy (nicotine patch, nicotine gum, nicotine spray, nicotine inhaler, nicotine lozenge) or prescription smoking cessation medications, including, but not limited to, varenicline (Chantix\*) or bupropion (Zyban®) within the past 30 days. If female, participant is pregnant, nursing, or intends to become pregnant during the time period from screening through the end of study. * Has participated in a research study about tobacco products or ENDS within the past 30 days. * Has participated in a smoking cessation or nicotine switching research study in the past year. * Smokes or vapes cannabis more than once a week. * Cannabis Use Disorder Identification Test-Revised (CUDIT-R) score of 8 or greater. * Heterosexually active participants of Childbearing Potential (not sterilized by tubal ligation, oophorectomy, hysterectomy, or other surgical methods, or post-menopausal) that do not agree to practice medically appropriate methods of birth control (or remain abstinent) during the course of the trial. Medically acceptable methods of birth control include: vasectomy, vaginal diaphragm with spermicide, intrauterine device, hormonal birth control (oral, injected, or implanted), condom with spermicide, or sponge with spermicide. * Subgroup enrollment is complete.