The 9005 and 9012 bulbs are not interchangeable as they have different base sizes and fitments. The 9005 bulb has a P20d base and can be used in a high beam 9012 applications, while the 9012 bulb has a P22d base and is typically used in low beam applications. If you are looking for an alternative bulb for 9012, 9006 will fit and work in place of 9012.