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

• [Premium Quality] Constructed of food grade material with 304 stainless steel 1/4″ barb to ensure durability, no rust or leak.
• [Easy to Use] Easily attaches to plastic bottles, gas (grey) ball lock connectors, or liquid (black) ball lock connectors.
• [Lightweight & Portable] The carbonation stone is lightweight, makes it more portable than traditional carbonation system.
• [High Efficacy] With the help of aeration stone, your beverage can be carbonating easily and is available to drink almost immediately.
• [Various Usage] Carbonation caps can carbonate multiple beverages, including beer, soda, wine and juice.