Current cigarette smokers (N=40) will sample three e-liquids within a single lab session, with different PG/VG ratios, complete a battery of questionnaires to assess sensory characteristics, product appeal, and reinforcement value. Participants will then complete a lab-based preference task to assess reinforcement value in which they choose between the three e-liquids. Finally, participants will receive one of the three e-liquids to take home for a one-week sampling period. During that week, we will assess e-cigarette and cigarette use. Participants will return the lab at the end of the week to complete additional questionnaires and return any unused product.