SAFE SHELTERS- Half Log animal shelters cut from safe, non-toxic Aspen. A renewable resource from the Colorado Rockies, Aspen DOES NOT CONTAIN HARMFUL OILS OR TARS like Pine or Cedar. The smoother bark is easy to clean and keep free of harmful dirt and bacteria. Corner cut base so that these may be placed in the corner of a cage and angled outward for better viewing of the animal 4 sizes: small, medium. Large, and x-large. .