The exclusively designed cleaning pads are made of a 100% non-woven viscose material specially processed using air-spun technology. This makes the Carboy Cleaner cleaning pads super absorbent, lint free, strong, yet soft enough that it will not scratch any fine surface. Use with: 3 – 6 gallon (12 – 23 liter) Carboys, plastic (PET) Better Bottles™, Slim Quarter & Sixth Barrel Kegs. Comes with small size bung medium size for PET Better Bottle is available separately. Effective cleaning diameter: +/-32 cm.