This is for a 2 Pack of Advanced Nutrients pH Perfect Sensi Grow Part B 1-2-6 500 ml 1 pt The ingredients found in Sensi Grow Part B are specially formulated to promote rapid growth, sturdy structure, and lush foliage in all of your valuable plants. By using pH Perfect Sensi Grow, the consistent two-part base nutrients formula will promote a reliable and satisfactory harvest in even the most productive hydroponics gardens. If you follow the label directions, pH Perfect Sensi Grow Part B will keep the pH of your nutrient solution stable within a range optimal for nutrient uptake for one week. For optimal results, we recommend using reverse osmosis (RO) water or water up to approximately 100 ppm (EC 160 ?S/cm). This product has been specially designed for use with diverse hydroponic growing media, including peat, rockwool, and expanded clay pellets, and all continuous liquid-feed growing systems such as aeroponics, drip irrigation and emitters, NFT, flood and drain, and deep water culture. Because this product contains our proprietary pH Perfect Technology, we?ve eliminated the need for pH and ppm metering, making pH Perfect Sensi Grow Part B an invaluable asset to your grow room.