What is the Borosilicate Glass? Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents.Borosilicate glasses are known for having very low coefficients of thermal expansion, making them resistant to thermal shock, more so than any other common glass. Such glass is less subject to thermal stress and is commonly used for the construction of reagent bottles. At present, our company leads in the technology of high borosilicate glass in domestic market. SIXAQUAE glass products adopt high-borosilicate heat-resistant glass refined, safety non-toxic, ensure health. DURABLE & BEAUTIFUL DESIGN BREWING MADE EASY TASTE THE DIFFERENCE! WHY CHOOSE SIXAQUAE SIXAQUAE All About The Coffee,French Press,Moka Pot,Cold Brew,Glass Jar.Health and Safety Are Our Top Concern,NON-TOXIC&BPA FREETeamwork With The Italian Design Team To Provide The Latest Coffee Product Design For Customers. ADD COFFEE POWDER Add the ground coarse coffee powder to the filter, about 1/4 of the way up the filter ADD WATER Slowly pour room temperature filtered water over the coffee grounds,until the water level exceeds the glass part to stop adding water COLD BREW Allow the coffee to brew in the refrigerator for 12-24 hours ENJOY TIME Open, remove the filter with coffee grounds, and enjoy the coffee next