When replenishing your Detergent Activators it is recommended to replace your BurstFiber brushes as well. The Brush and Activator Combo is the perfect way to ensure your StormStick Decon System is stocked and ready for operation. The 2x2 kit includes 2 boxes of 15 Detergent Activators and 2 BurstFiber Brushes. The 4x4 kit includes 4 boxes of 15 Detergent Activators and 4 BurstFiber Brushes. The 8x8 kit includes 8 boxes of Detergent Activators and 8 BurstFiber Brushes.