TyreBeads Tire Balancing Beads - 4 bags of 5 oz (20 total) fits 4 tires + FREE Applicator Kit. Includes 4 bags of 5 oz each (20 oz total) + FREE Installation / Applicator Kit, FREE Filtered Valve Cores, FREE Red Caps These are premium internal tire ceramic balancing beads. Reusable, super hard, durable, and eco-friendly - will not rust, clump, or melt Pour them in during mounting or apply through the stem. Good rule of thumb is 1 oz per 10-12 lbs of tire THESE ARE NOT GLASS, which is a softer material that has a tendency to break down into powder, which is susceptible to clumping and is a health hazard.