HFS (R) Twin Fitting, Adapter 1/4″ male SAE 37 Degree Flare to 1/4″ Male NPT ; Stainless Steel 304
These fittings could be used for a lot of things including putting together a Spunding Valve Build. A Spunding Valve allows you to ferment under pressure, naturally and precisely carbonate in the keg, fix over-carbonated beers and more.
See: [Build a Spunding Valve]. Take a look at Build Option 2 for a version that uses a similar although not identical fitting.
9/12/18 8 AM Central: This is selling for just $6.99. Shipping is also free to many US addresses. Prices, shipping and availability can change quickly. Please note that product prices and availability are subject to change. Prices and availability were accurate at the time this this post was published; however, they may differ from those you see when you visit Amazon. Check the product page for current price, description and availability.
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