The green-lined tray has a raised area at the bottom to keep the growing cell tray well drained and allow the bottom to be watered. STURDY MATERIALS & REUSABLE: The seedling tray is made of plastic material, and not fragile, thickened bottom material, can withstand pressure, not lose soil or absorb too much water, effectively nurturing seeds HUMIDITY CONTROL LID WITH AIR VENTS: Our nursery box is designed with adjustable circular vents, which is easy to maintain the humidity and warmth required for seedlings to GOOD OVSERVE for EACH PLANTS GROWTH: The seedling tray is used to raise seedlings, which is convenient for centralized management. The transparent tray is convenient for observing the plants and can keep warm and moisturize, and can be stacked together to save space when not in use., Manufacturer: PokFhgur