Rockwool Grow Cubes (1.5 Inches) - Growing Medium Starter Sheets (30 Per Pack) Inorganic & Sterile Growing Medium A Superior Medium For Rooting Cuttings Encourages Faster Initial Rooting & Its Firmness Is Guaranteed Provides 20% Air Space When Saturated - Absorbs nutrient solution while retaining plenty of oxygen for rapid root growth! Cubes Measure: 1.5" x 1.5" x 1.5"