Package Content - 4 x seed tray with 12 holes, snaps over the two bottom trays quite nicely.Seed Tray - 12-cell insert tray provides a simple, straightforward way to sow seeds and raise plants from cuttings.Base Tray - Ideal for use when propagating to catch the excess water that drains from seed trays. Also great for hydroponic use. You can fill the bottom with water and it is distributed to the right places, so the roots can absorb the water.Transparent Dome - Transparent lid plays roles of humidity and warmth, allow you can see seedlings' growth process clearly.Keep Seeds Grow Healthy - Seeds need a suitable space to improve their absorption of water and nutrients. These propagator set maintain different climate conditions for groups of seedling and ideal to transit room temperatures for optimal root growth.