System Three Glass Microspheres, 1 Quart are hollow, clear, microscopic spheres designed to serve as bulking agents that provide a low-cost, low-density filler option. When added to epoxy resin and hardener mixtures, they create a heat-resistant, lightweight fairing compound with excellent compressive strength. This mixture can be enhanced by blending in a small amount of Silica Thickener to prevent sagging. While these microspheres are not for use as glue, an product, SilverTip QuikFair, ease of use for such applications. The product comes in a convenient quart container and is made in the USA. Model Number: