The provided Ignition Coils are opposite of ordinary gear trains; in case of larger reduction ratios, the direction of transmission is not reversible. All the parts and components are made in standard sizes / dimensions that ensure compatibility with all brands of automobiles. These Ignition Coils have industrial usage and have a standard shape, which makes them compatible with all the vehicles. This is an enclosed metal casing, wherein a series of rack and pinion gears are installed.