 From Day 1 to the end of the study all subjects randomized to an e-cigarette cohort were allowed to carry the assigned product with them throughout the day and use their product ad lib within identified sections of the clinic. Subjects randomized to the dual-use cohorts were allowed to smoke no more than 50 of the number of cigarettes per day reported at Screening. Cigarettes were were provided to the subjects upon request to the study staff. 