3 Inch Net Pot and Grodan A-Ok 1.5 Inch Starter Plug (4 Pack), plus Clay Pebbles Combo Four 3" high by 2.5" wide mesh net pots, Four Grodan Rockwool A-Ok 1.5" Starter Plugs, plus enough clay pebbles to use in conjunction with the rockwool plugs. This combination is perfect for hydroponic applications. The pot is made of durable, UV-resistant plastic, with numerous but narrow slits that properly contain appropriate-sized grow media. Grodan A-Ok Starter Plugs for seeds and cuttings provide an optimal media for root growth and is used prior to plugging into the larger Gro-Blocks. Made of 100% natural clay. The pebbles are of uniform, round shape, and is inert, pH-neutral, clean and decorative.