Ruff Landâ„¢ kennels feature one-piece roto-molded construction from UV-stabilized polyethylene. This means no assembly and no bolt-through ledge (as on two-piece kennels) which saves up to 3 inches of side space. It also makes for a much stronger kennel. And, because there are no seams, it is also much easier to clean. Finally, a Ruff Land kennel won't crack even in extreme subzero weather.