Made in the UK by Ladbrooke, the Micro 20 Soil Blocker is a hand-held device that is pushed into a wet soil mix. Squeeze the handle, and it ejects 20 individual blocks of soil measuring 3/4 inch on each side. On the top is a dimple that will receive one seed. Soil blocks allow the roots of plants better freer access to oxygen. When the seedling is ready, it is potted on into a 2″ soil block, and so on, before transplanting into the ground. Use this blocker to germinate your seeds. You can fit 300 mini blocks in a standard tray which will fit on one heating mat. Use one seed per block. After the first true leaf has formed, put the mini block into a two inch block. No transplant shock. No more plastic trays!