Polypropylene pellets have been used for many years to cushion loads of softer materials like obsidian. They tend to embed with Silicon Carbide particles, so they may be re-used only with the same size grit. Pellets used with 80-grit SiC thus should not be used with 220-grit, or 600-grit, but they may be reused with any 80-grit loads. Many customers still like them, even though the more modern Ceramic Shapes have largely replaced them. This is 0.5 Lbs of white, 1/8-inch diameter polypropylene pellets , at $6.06/Lb, in a 1-pint plastic container.