The granularity gets coarser as the number gets smaller. This means polishing will have more effect. Conversely, the larger the number, the coarser the grinding effect. It is advised to use this item according to its characteristics and polishing requirements. Material and Size: Made with high density sponge as well as small alumina emery. It can be easily washed and reused. Each piece of standing sponge measures approx. Fine workmanship - surfaces have been coated with tiny alumina emery. Not only durable but also reusable. The interior contains a durable high density sponge. Very solid. They are also highly resistant to acid, alkali, wear and water.Usage and Storage: Perfect for use in both wet and dry form. They can be used to polish a wet object surface. The sponge has a very nice cleaning and polishing effect. It can be adjusted to perfectly fit any shape, thus avoiding waste. Please make sure the water is extruded out after use. After that, should be placed in a ventilated and dry place. This will help ensure that it lasts as long as possible.Nice polishing tool perfect for polishing wood, amber and metal and cleaning kitchen appliances. The sponge is perfect and can work on uneven and flat surfaces. Please note that it should not be used on a boiler liner (high grain non-stick) surface. Note: The data are all manual measurement, please allow error of 1 - 3cm, due to the difference in light and display, there will be a certain color difference, depending on the physical object received.