Heavy gauge ribbed glass filtering funnel is made of pressed glass and fire polished. Allows air to escape the container while you fill it… for smooth, glug-free filling. Hand Made in the USA The raw materials are mixed on site. The main ingredients are Silica and Soda Ash. The mixture is shoveled into the furnace and melted at about 2500 degrees Fahrenheit. When the glass is ready to work with it is gathered out of the furnace by hand and cut off into the mold and pressed. After the piece comes out of the mould it is then placed onto a glazer. The glazer is a fire polishing process. After the glazer, the piece is put into a lehr, which is a annealing process to cool the glass slowly so it doesn’t crack or bust. The cooling process takes about 3.5 hours and then the pieces are checked and packed. Measures 5.75 inches Inside Diameter