This insert and tray has been completely redesigned and is considered to be the best on the market. Not only is it filled with ROOT!T Natural Rooting Sponges, it is tough and durable whilst also not allowing any pooling. It really does help to grow big every time. It has large drain holes to facilitate easy de-plugging and have specially designed irrigation channels to rapidly remove excess water. This kit is made from fully recyclable HIPS (high impact polystyrene) and it fits standard seed tray size propagators.