3 3/8" x 4" STAINLESS STEEL FLASK FOR METAL CASTING Stainless steel perforated flasks are utilized for vacuum casting machines. They are made of quality medical grade stainless steel and withstand well corrosion of burnout and thermal shock of casting. The perforations allow the vacuum to penetrate through the walls as well as the bottom of the flask. This produces castings of higher density, reduces the chance of air entrapment and results in more of a complete fill. Wall thickness: 2mm 3 3/8" x 4"