Features: Brand New and High Quality Easy set up, Simply, Nano, Excellent disign! Attached with high quality plastic "O" ring inside of the cap to prevent missing the Co2. This bottle cap is very suitable to be DIY Co2 system’s accessory that the size fits common PET plastic bottle. Specifications: Material: Plastic Color: Beige Item Size: 3.4*3.4*3.2cm Package included: 1 X Bottle Cap