1. Prevent fuel from returning to tank and keep it in line. 2. Suitable for carburetor and low pressure fuel system. 3. Easy to install and replace. 4. OE: 058905291K 5. Applicable models: For 2001-2001 AUDI A4 AVANT CONFORT WAGON 4-DOOR For 2001-2001 AUDI A4 AVANT LUXURY WAGON 4-DOOR For 1998-2000 AUDI A4 AVANT WAGON 4-DOOR For 2004-2005 AUDI A4 AVANT WAGON 4-DOOR For 1997-2005 AUDI A4 BASE SEDAN 4-DOOR For 2001-2001 AUDI A4 BASICO SEDAN 4-DOOR For 2003-2005 AUDI A4 CABRIO CONVERTIBLE 2-DOOR For 2003-2006 AUDI A4 CABRIOLET CONVERTIBLE 2-DOOR For 2001-2004 AUDI A4 CONFORT SEDAN 4-DOOR For 2005-2005 AUDI A4 ELITE SEDAN 4-DOOR For 2001-2005 AUDI A4 LUXURY SEDAN 4-DOOR For 2004-2005 AUDI A4 S LINE SEDAN 4-DOOR For 2005-2005 AUDI A4 S LINE SPORT SEDAN 4-DOOR For 2001-2001 AUDI A4 SPORT SEDAN 4-DOOR For 2005-2005 AUDI A4 TRENDY SEDAN 4-DOOR For 2003-2005 AUDI A4 VANGARD SEDAN 4-DOOR For 1998-2005 AUDI A4 QUATTRO AVANT WAGON 4-DOOR For 1997-2005 AUDI A4 QUATTRO BASE SEDAN 4-DOOR For 2004-2005 AUDI A4 QUATTRO CABRIOLET CONVERTIBLE 2-DOOR For 2001-2001 AUDI A4 QUATTRO CONFORT SEDAN 4-DOOR For 2005-2005 AUDI A4 QUATTRO ELITE SEDAN 4-DOOR For 2002-2002 AUDI A4 QUATTRO LE MANS SEDAN 4-DOOR For 2002-2005 AUDI A4 QUATTRO LUXURY SEDAN 4-DOOR For 2005-2005 AUDI A4 QUATTRO S LINE SEDAN 4-DOOR For 2007-2008 AUDI S6 BASE SEDAN 4-DOOR