More products from: Grodan
Macroplugs are great for plant cloning or starting seedlings.
The round stonewool (rockwool) plug has a slit from top to bottom that lets you easily insert a plant cutting or a seed.
The fibrous structure of a Macroplug creates an ideal air-to-water ratio that encourages robust root development.
When the roots of your plants start to outgrow the plug, simply place the Macroplug into the pre-drilled Delta Gro-Blocks to enlarge the growing media area.
Grodan Macroplugs measure 1-1/2" in diameter.
More info from the manufacturer (PDF format)