Higher Nature Colloidal Silver Spray Refillable 15ml Our Colloidal silver contains pure, medical grade silver, which has been used for many centuries. It is produced using electro-controlled technology and pure water from a 9-stage water purification process, to achieve a very small particle size (0.0006 to 0.005 microns). This small particle size is important because it provides a much greater surface area and therefore more of an effective liquid. The 15ml refillable size is ideal for carrying in a bag or pocket. Use the 200ml non-spray-nozzle size to refill the 15ml and 100ml spray-nozzle sizes. This product has remained exactly the same for many years and continues to be colloidal silver of the highest purity and quality.