TyreBeads Tire Balancing Beads - 1 bag of 4 oz -Truck/Motorhome/4x4/Trailer/Motorcycle Includes one 4 oz bag 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. 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.