I HATE "what's in the box" threads.. I won't do that to you guys lol.. Its "java" wood. They are bird perches. Dense, safe (birds chew on them), they grind off all of the rough edges and its waay cheaper than wood at fish stores. The bottom has a stainless steel wing nut. I am drilling the top of the tank and mounting them upside down like roots. The bottom stays open for the fish to roam.