Our 15 ml Polystryrene Sifter Jars with Caps can be used alone, but are best suited to be used with our 15 ml Jar Sifter Inserts (purchase separately). The Sifter Insert makes it easy to control the amount of powdered cosmetics that you apply to your brush. They are perfect for use with shadows, blushes, bronzers and foundations. Simply place your powdered cosmetic and the corresponding sifter into our 15 ml Polystryrene Sifter Jar. These practical 15 ml jars hold the equivalent of 0.50 fluid oz.