The Super Sprouter Root Raft is designed to be a self watering starter tray. Root Raft includes a 10 x 20 inch tray for holding water and a styrofoam 55 site floating insert loaded with Super Sprouter custom blended and custom sized grow plugs. Mother Earth BioChar added to this exclusive formulation. No worries about watering — moisture is automatically wicked through the plugs. Floating grow tray! Just fill the tray and walk away. If you desire a mini greenhouse effect, you can use any of the Super Sprouter domes to get the job done. Domes sold separately.