The fertilization box is made of stainless steel, which has the service life. - Easy to use. You only need to insert directly into the growing soil that your bonsai is in. - The product comes with the tip head design, making it convenient to insert into the soil. - Each one is made by exquisite craftsmanship to meet your -term use and replacement needs. - Portable reusable is easy to use, just put the directly into the bonsai soil and water. The dissolves into nutrients for the plants.