Inclusion Criteria:  Provide informed consent Be at least 21 years of age or older Provide a breath sample for measuring carbon monoxide (CO ≥ 8 ppm) Stable tobacco use patterns for at least three months Be willing to sample NVPs, HTPs, and NPPs.  For exclusive cigarette smokers:  - Smoke at least 10 cigarettes daily and do not use NVPs regularly (no more than 9 times in the last month).  For dual cigarette/NVP users  - Smoke at least 5 cigarettes daily and use NVPs for at least 3 times in a week (report use of closed nicotine salt system)  Exclusion Criteria:  Have plans to move out of the area Have a serious or unstable physical or mental health condition Taking a tobacco cessation medication or medication that interferes with nicotine metabolism, motivation or reinforcement Report concrete, immediate plans to alter/quit using their usual nicotine products at the beginning of the study