3M™ Glass Bubbles HGS4K28 are hollow microspheres made of soda-lime borosilicate glass with a true density of 0.28 g/cm³ and an isostatic crush strength of 4,000 psi / 280 bar.
HGS4k28 Glass Bubbles are designed for use in drilling, completion, and workover fluids, as well as in cement slurries from shallow to intermediate depth waters in the oil and gas industry.