The size of this product is 4 x 5Kg stabilised chlorine granules (sodium dichloroisocyanurate) are a great way to raise the chlorine level in your swimming pool whilst having almost no effect on the pH and at an incredibly discounted price too. Always read and adhere to the instructions on the pack and never directly mix chemicals. Don't forget, the price you see is the price you pay not a penny more. We sell chemicals cheap, not cheap chemicals!