Joebonsai Genuine Red Lava Gravel Bonsai Tinyroots-Brand Top Dressing AND Humidity Tray Gravel One Pound Great For Bonsai Landscaping/Design Ph Balanced All-Natural Can be used on top of soil or in a humidity tray. Great for Bonsai trees, or any other type of plant. Genuine crushed red lava gravel. Porous lava increases airflow. Ph Balanced for root health, 100% natural, no chemical treatment. Will not break down over time. Three Cups (1 lb) of gravel, Covers roughly 1 square foot. Direct from Bonsai Outlet, the Internet's largest Bonsai retailer, Money-Back Satisfaction Guarantee.