3M™ Glass Bubbles K15 are hollow microspheres made of soda-lime borosilicate glass with a true density of 0.15 g/cm³ and an isostatic crush strength of 300 psi / 21 bar.
These additives are designed for a variety of applications including buoys and moorings, polyurethane and epoxy resins for tooling boards, paints and coatings, construction materials, and emulsion explosives.