"Essentials" Soil Blocking Kit with Mini 4, Micro 20, Cubic Inserts, 1" Seed Dibbles, Grow Tweezers Soil Blockers are easy and fun to use. Environmentally friendly by reducing non-renewable plastics. Used extensively for germinating seeds in Europe. The Micro 20 3/4" blocks "nest" into 2" Mini 4 blocks. Set also includes set of Cubic Inserts, 1" Seed Dibbles, Grow Tweezers. Soil blockers are by Ladbrooke, makers of the highest quality products that will last for years!