(For lack of a better term) the Flow Pop Up refers to the 2 x 2 grid view that is accessible by clicking the expiration date of any options contract across the website. The 2 x 2 grid provided by the Flow Pop Up is also accessible via the Chain Explorer.

Top left: Options Contract Volume Chart
 

The top left card provides a volume chart for the respective contract. Using the dropdown on the top right of the card you can view historical data (up to 60 days) and change between timeframes.

Candles can be hovered over for more information. Clicking a candle will open a new window taking you to the flow feed for the selected period. 

Top right: Stock Chart / Options Volume Chart / Net Premium Chart / Averages

The top right card provides 4 different types of charts for the respective equity. Using the dropdown on the top right of the card you can toggle between charts, days displayed, and timeframes. Selecting some charts will provide additional functionality.

Bottom left: Options Contract Historical Volume and OI Table

The bottom left card provides a table displaying historical data for the respective contract. Using the buttons on the top right of the card you can configure the shown columns, as well as make the table longer. 

Bottom right: Equity Historical Data
 

The bottom right card provides a table displaying historical data for the respective equity. Using the buttons on the top right of the card you can configure the shown columns, as well as make the table longer.