From the release:
Latest release in our WWII scenic range:
15A40CB: Large vehicle scenic bases (urban)
A set of two bases cast in tough polyurethane resin and beautifully sculpted with a marked urban theme.
Designed to accommodate extra large 15mm vehicles (like tanks!) that would not fit on standard medium bases, these are the same size of a large FoW base and so are also perfect to base heavy artillery or to make your own objectives!