are horizontal, stainless steel beer-serving tanks that are designed to be filled via transfer hoses from mobile, usually truck-mounted, beer delivery tanks. The Bier-Drive system was developed and patented by the German company EDS Schwiekowski of Schöningen in Lower Saxony in the 1970s. It is designed for the convenient delivery of bulk quantities of ready-to-serve beer from the brewery to large on-premise accounts, much the way tank trucks deliver heating oil to private households and businesses. The system is very economical and practical because it eliminates the need for kegs, which are always expensive, labor intensive to clean and to fill, heavy to handle, and often stolen for their scrap-metal value. Bier-Drive tanks come in sizes of 500 and 1,000 l (132 and 264 US gal) and, just like beer tanks in brewery cellars, they are manufactured for various pressure ratings (up to 3 bar), as well as with and without cooling jackets for either ambient or individual tank cooling. Unlike brewery tanks, however, Bier-Drive tanks have a disposable plastic inner liner, which keeps the beer from making contact with the inside tank wall. The liner is replaced every time the tank is filled. Thus, a Bier-Drive tank does not need to be cleaned and sanitized. Also, the beer is less likely to get infected by microbes and protected against undesirable uptake of the gas—be it air, carbon dioxide, or nitrogen—used to pressurize it. The beer is pushed out of the tank to the dispensing tap by means of air or gas applied between the tank and the plastic liner. Because Bier-Drive tanks can also be used as serving or bright tanks without the liner, they are much sought after as used equipment by brewpubs.