Packed in a case of 12. This style of bottle is also commonly referred to as a Grolsch style bottle, and known as de beugel or 'swingtop'.
The top used to be made of porcelain, but is now made of plastic. Bottles with porcelain tops are still in circulation in the Netherlands. They are popular with home brewers.
The new design can also accommodate Crown Caps sold separately.
Grolsch bottles are becoming increasingly prevalent. The bottles seal with a plastic, gasket lid and a wire bale (included).