From the release:
Volcanic Rifts is a printable dungeon floorplan compatible with any RPG/Dungeon-Crawl game. It can be used as a standalone gameboard, or combined with any same-scale tileset.
Volcanic Rifts is a geomorphic set, comprising 6 10x10 square battlemaps which can be arranged in multiple layouts. Each tile features magma-filled rifts and fissures in a bleak volcanic landscape, cracks that might pour with lava at any moment.
Also included is a set of 300dpi full size jpgs, for poster printing or VTT, with both gridded and non-gridded versions (n.b. non-gridded version only available as full jpegs)