Car manufacturers started using ATC / ATO blade fuses in vehicles starting in the 1980s. They are still used extensively in recreational vehicles All Terrain Vehicles (ATVs) boats as well as electrical and HVAC applications. They provide safe and reliable circuit protection from everything to your headlights to your trunk release. All fuses are color coded to identify their amp rating. This ATC / ATO fuse is blue to indicate it is a 15 amp fuse. Ensure that you always replace an open fuse with one of the same amp and voltage rating and style/dimension.