From the product description, check product page for current description, price and availability:

• Made in Germany of a very high quality fiber plastic. Extremely Durable
• We have tested them and they showed no signs of wear after repeated tightening and Un-tightening of regulator to CO2 bottles
• Includes pin that allows you to attach to regulator so they won’t fall off when changing out cylinders
• Affordable product that allows you to leave it on your regulator permanently!
• Fits Standard American Beer Regulators

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