This line shapefile displays graticules (grid lines of latitude parallels and longitude meridians) for the world at 30 degree intervals. Graticules include 180-degree east and west meridians (consider deleting one of these to avoid duplicate lines). This layer is part of the Natural Earth Collection (v.2.0.0). Scale:110,000,000., Natural Earth is a public domain map dataset available at 1:10m, 1:50m, and 1:110 million scales. Featuring tightly integrated vector and raster data, with Natural Earth you can make a variety of visually pleasing, well-crafted maps with cartography or GIS software.
Patterson, Tom, Kelso, Nathaniel Vaughn (2012). 30-Degree Graticule Grid, World, 1:110 million, 2012. North American Cartographic Information Society. https://purl.stanford.edu/sp849zn9115 (dataset)