Description Made from molten rock spun into cotton candy-like fibers and then compressed into cubes. After high temperature treatment, non- and sterile. The bulk density is small, the texture is light, and the porosity is large. Good air permeability, strong water absorption and good drainage. Suitable for the cultivation and colonization of all kinds of plants. Color: yellow Great choice for soilless planting. Material: rock wool Size: about 27 x 20mm Instructions: Preparing and planting in rock cubes. Soak in water for 2 minutes. Take out from the water and place for about 15minutes. Put seeds into the hole of cubes. water after seed inserted. Place it in a seed tray. Package Contents: 50 x Cubes Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.