Why would these have anything to do with homebrewing, you ask? Great question. These are an easy way to measure 6 mL of Star San. Put 6 mL of Star San in 1 gallon of distilled water and you’ve got sanitizing solution. Fill up a spray bottle and you’re ready to sanitize for pennies a batch. See: Star San Tips, Tricks and Guidelines
6/29/20 3 AM Central: These are selling for $4.58. Shipping to most US addresses also is free. 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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Make sure the components you use are compatible and rated for your intended application. Contact manufacturer with questions about suitability or a specific application. Always read and follow manufacturer directions.