Searching of CO2 Bottle Caps? Our CO2 bottle caps will be the for you. Made of high grade ABS material, durable enough for your long-term use. Practical and portable design, its popularity. ABS material makes this bottle uneasy to rust and safe for your fish and water plant. And it can be your good helper. Features -Color:Beige -Material:ABS -Size:5.50X4.00X4.00cm/2.16X1.57X1.57in - Easy to set up, and high grade materials, can be used for a long time. - Made of high-grade materials, safe and durable, you can use it with confidence. Standard , widely applicable. - Easy to use. Just screw the bottle on the drink bottle. Easy and sealed without letting the air out easily. - For people who love DIY CO2 setup, the bottle caps are helper when they are doing the process of generating CO2. - These CO2 Bottle Caps are suitable for most kinds of carbon dioxide DIY reactor. Package list: 2 x Bottle Caps 2 x Sealing Rings