Grodan Improved Stone Wool Delta Starter Mini-Blocks - 2 inch x 2 inch x 1.5 inch CaseGrodan Improved Stone Wool Delta Starter Mini Blocks 2 inch x 2 inch x 1. 5 inch Grodan Improved Stone Wool Delta Starter Mini Blocks are the perfect solution for gardeners looking for a superior alternative to traditional starter cubes. These 2" x 2" x 1. 5" blocks are designed to deliver perfect drainage, uniform and high quality plant starts, increased initial root mass, and reduced transplant shock. Each block boasts a virtually identical density,