* Material: PU * The weight of the pumice are light, it will float on the water. * You can tie the sucker with the rope of the pumice, then dragged into the water, make the sucker griped the bottom of the tank to build the suspernsion landscape. * The base material of grow plants, pumice surface has many holes and can be contact large area, can absorb the water harmful bacteria and heavy metals, conducive to plants climbing and take root.