Check the listing for details. ( 100 x ) 25 x 35 mm Jiffy 7 Peat Pellets Seed Start Starting Hydroponic plug. Condition: New. Listed at 10.20 USD. 100 pcs Jiffy-7 25 x 35* mm (1" x 1.5" Diameter x Height) peat pellets. The Jiffy-7 pellet is made from the peat (sphagnum peat) from specially selected bogs. The peat is designed to stimulate growth, and the pellets have a 5.3 pH. Each pellet is enveloped in a degradable net, making it ideal for starting seeds. Hydroponic Media.To begin, After you add water**, the pellet will expand to 1" in diameter and 1.5" tall in 3-5 minutes. After it has expanded, you are free to plant it (place a couple of seeds in the pellet and push 5-10 mm down ) . Jiffy pellets make the transfer simple and easy, all the while providing the seed with nutrition and preserving its root. * 6 mm thick before add water** 10 pieces need about 2/3 cup of water.