BACKGROUND: Little is known about the characteristics of electronic cigarettes (e-cigarettes) used by adolescents. Understanding the product landscape of adolescent e-cigarette use may inform counseling and policy strategies. METHODS: Results are from 13 651 adolescents in wave 1 and 12 172 adolescents in wave 2 of the Population Assessment of Tobacco and Health Study, a nationally representative longitudinal study. Past 30-day regular e-cigarettes users were asked about the characteristics of the e-cigarette they used most of the time. RESULTS: In waves 1 and 2, 2.1% and 2.8% of adolescents were regular users in the past 30 days, respectively. These adolescents more often used rechargeable rather than disposable devices (wave 1: 76.0%; wave 2: 82.9%) and refillable rather than nonrefillable devices (wave 1: 66.6%; wave 2: 84.4%) and tended not to use cartridge systems (wave 1: 33.7%; wave 2: 30.5%). Most adolescent past 30-day users (wave 1: 87.5%; wave 2: 89.4%) reported using flavored e-cigarettes. An increased frequency of use was associated with the use of rechargeable (wave 1 adjusted odds ratio [aOR]: 2.7; wave 2 aOR: 2.7) and refillable e-cigarettes (wave 1 aOR: 2.0; wave 2 aOR: 2.7; P < .05). Most users in wave 1 did not continue regular use in wave 2 (70.2%). Among those who continued to use and had reported using closed systems (nonrechargeable and/or nonrefillable) in wave 1, most had progressed to open systems (rechargeable and refillable) in wave 2. CONCLUSIONS: Most adolescents use open-system e-cigarettes, and frequent users are even more likely to use open-system e-cigarettes. The majority of regular users use rechargeable devices that are refillable. A change in product preferences across waves suggests a starter product phenomenon, with a graduation to products that have weaker quality controls and may increase health risks.