Interrupted transverse Mercator projection with central meridians at 165°W, 75°W, 15°E and 105°E. 15° graticule.
This interrupted arrangement of the transverse Mercator projection uses SVG masking to show extended detail beyond the interrupted regions in light grey.
Victor Schrader came up with this arrangement in the 1960s, and explains:
The extension of map detail beyond the 90° gores minimizes discontinuities produced by this interrupted arrangement of the graticule.
—Victor Schrader, World Map on an Interrupted Transverse Mercator Projection, The American Cartographer, Volume 16, Issue 4, 1989.