This interactive scatter plot matrix lets users brush rectangular regions across any pair of dimensions to filter the displayed data points. The visualization initially shows all observations as colored circles across every pairwise combination of variables, with histograms along the diagonal for each dimension. Users can drag to create a brush selection in any plot, which immediately highlights matching points in all other plots while dimming non-selected ones. Built with D3 v6, the example uses `d3.brush`, `d3.cross`, `d3.scaleLinear`, and SVG rendering, with colors mapped via `d3.scaleOrdinal` and `schemeCategory10`, using the v3 dataset.