These are glass balls for stirring paint (4mm diameter). Simply put an appropriate amount into the paint bottle and shake to stir the paint. Because the diameter is smaller than conventional steel balls, the bottle is less likely to break. Also, because they are made of glass, the paint is less likely to deteriorate. Especially for metallic paints containing aluminum, glass balls are recommended as there is a risk of galvanic corrosion with commercially available steel balls. Due to their 4mm size, they can also be used for detail-up depending on the application. They will be shipped in a zip-lock bag. Please note that there may be slight variations in the number of pieces due to the small size of the product.