This radar chart compares weekly usage percentages of 21 smartphone and tablet services, such as email, social networks, and online gaming, across two data series. It renders a multi-level circular grid with axis labels and value markers, using D3 v3’s selection and data join APIs to draw SVG polygons for each series. The chart supports click and double-click interactions that adjust fill opacity to highlight or reset series. A separate legend identifies the two devices by color, sourced from an ordinal color scale.