The FloraFlex� FloraCap� 4, 6 or 8 inch helps eliminates algae, stops powdery mildew and does away with pesticides. Place the revolutionary, FloraCaps� on your rockwool cubes, and maximize your space in the vegetative cycle. Each cap features 34 flower designed louvers for 6 & 8 in and 17 flower designed louvers for the 4 in, to block light, while allowing air, water and nutrients to your plant. Feed your plants less, allow the root zones to dry at more consistent rates with the FloraCap� that strategically covers the top of the media, while allowing in the necessary oxygen they need to thrive. Made from BPA and lead-free plastic. Dishwasher safe, stackable and reusable.