Electronic nicotine delivery systems (ENDS) vary on a wide range of characteristics, which may impact the reinforcement value of the products compared to more harmful combustible products. A new type of low-powered ENDS device has surged in popularity-the pod system. Pods use nicotine salt e-liquids, rather than free-base nicotine solutions that have been used in other ENDS device types. Manufacturers claim that these formulations reduce the harshness of nicotine delivery, while still delivering sufficiently high levels of nicotine. However, the role of nicotine salts in the popularity and use of pod systems remains unclear because no studies have directly manipulated and examined the role of nicotine formulation (salt vs. free base) in reinforcement value and use. The primary purpose of the proposed study is to assess the impact of nicotine formulation (nicotine salt vs. free-base) in reinforcement value and tobacco use. Current smokers (n=30) will complete a one-week baseline period where they smoke as normal before attending an in-person lab visit during which they will sample a traditional cigarette and two ENDS products (nicotine salt ENDS, free base ENDS). All aspects of the device will be held constant other than the nicotine formulation (including nicotine concentration, flavor options, device brand). Participants will answer questionnaires about each product they sample and then complete a preference assessment in which they choose between the products they sampled and their own cigarette. Finally, participants will be assigned to take one of the products they sampled home to use ad libitum (1-week sampling). During the at-home baseline and sampling weeks, participants will complete electronic daily diaries cataloging their tobacco use. Biomarkers (i.e., expired carbon monoxide, cotinine) will corroborate self-reported indices of use.

Inclusion Criteria:

• daily cigarette smoker
• interested in using non-cigarette tobacco product
• have a smartphone that can receive text messages and has access to the internet or have an e-mail account they check daily (necessary for daily diary completion).

Exclusion Criteria:

• additional tobacco use criteria
• additional medical criteria

Neither the staff nor the participants will be told whether the e-liquid is free base or salt based.