Kellerbier is German for "cellar beer". Zwickelbier was originally a sample amount of beer taken by a brewery boss from the barrel with the help of a special pipe called a Zwickelhahn. Zwickelbiers are unfiltered lagers like Kellerbiers, though with a slightly different conditioning process, which gives the lager more carbonation. Zwickelbiers tend to be younger, lower in alcohol, and less hoppy than Kellerbiers. A very similar beer is Zoiglbier, which in the Upper Palatinate's brewing practice is advertised with a Zoiglstern (i.e., sign) — a six-pointed blue-and-white symbol made from wooden slats, similar to a Star of David. Münchener Bier is a beer from Munich that is protected under EU law with PGI status, first published under relevant laws in 1998. This designation was one of six German beers registered with the PGI designation at the time. Wheat beers Weizenbier and Weißbier are the standard German names for wheat beerWeizen is German for "wheat", and weiß is German for "white". Berliner Weisse is a pale, very sour, wheat beer brewed in Berlin. 9° Plato, 2.5–5% ABV. The beer is typically served with raspberry- or woodruff-flavoured syrup. Hefeweizen is an unfiltered wheat beer. Hefe is German for yeast. Kristallweizen is a filtered wheat beer, characterized by a clear appearance as opposed to the cloudy look of a typical Hefeweizen. Weizenbock is the name for a strong beer or bock made with wheat. 16–17° Plato, 6.5–8% ABV. Roggenbier is a fairly dark beer made with rye, somewhat grainy flavour similar to bread, 4.5–6% ABV. Breweries While the beer market is weaker but more centralized in northern Germany, southern Germany has many smaller, local breweries. Almost half of all German breweries are in Bavaria, where the seven main breweries produce annually. In total, about 1,300 breweries in Germany produce over 5,000 brands of beer. The highest density of breweries in the world is found in Aufseß near the city of Bamberg, in the Franconia region of Bavaria, with four breweries and only 1,352 citizens. The Benedictine abbey Weihenstephan brewery (established in 725) is reputedly the oldest existing brewery in the world (brewing since 1040). In 2004, Oettinger replaced Krombacher as the best selling brand in Germany. Alcohol content The alcohol-by-volume, or ABV, content of beers in Germany is usually between 4.7% and 5.4% for most traditional brews. Bockbier or Doppelbock (double Bockbier) can have an alcohol content of up to 16%, making