Grodan 1.5" Macro Plugs - Pack of 50 Rockwool Stonewool Plugs for Seed Starting, Plant Propagation & Cloning Cuttings Trusted Grodan 1.5" Macro Plugs made from premium spun rockwool Macroplugs have a slit that allows for easy insertion of a cutting or bare-root plant. Great for Seed Starting, Plant Propagation, Root Cuttings & Cloning Packaged in bulk to save you money! Can be easily inserted into larger rockwool cubes or slabs once roots develop