Goff's Enterprises Inc. (goffscurtainwalls.com) designed its Weld/Grind Cell as a freestanding, portable unit. The cell is open at the top, and is made of weld/spark-resistant curtain material that the company says meets the National Fire Protection Association's 701 test for retarding fires. It has galvanized steel hardware, and its midsection is made of 14 mm (0.55 in.) thick polyvinyl chloride sheet that meets the California Fire Marshall Test.