Grodan Multiblocks 1.4"x1.4"x1.5" Case 2950. Grodan A-Ok Starter Plugs are the caring home your seeds and cuttings need to get started. These A-OK plugs are designed for use before plugging into larger Gro-Blocks. Ensure your seedlings get started on the right track with Grodan A-Ok.36/40 also includes instructions for use of shrink wrap that fits a standard 10 x 20 inch tray (flat). 1.5 inch x 1.5 inch Plugs.