This Mr. Beer Deluxe Glass Bottling System include 11, 25 oz. premium-quality, reusable glass bottles. These bottles feature a lowered bottle rim that is specially designed to work with a hand capper, which is necessary to retain beer carbonation, as well as a thicker bottle wall to ensure safety during the carbonation process. To accompany the Glass Bottling System, Mr Beer offers a Bottle Capper and Caps kit which includes 75 metal crown caps and a durable hand bottle capper.