The product is a rare vacuum steam heating pressure relief valve manufactured by Norwall Mfg Co in the 1910s in the United States. This collectible piece falls under the category of plumbing and steam fitting tools, making it a unique and sought-after item for collectors and enthusiasts in the field. With the brand's history and the specific time period of manufacture, this valve holds value for those interested in vintage plumbing equipment and the craftsmanship of early 20th-century American manufacturers.
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