This Gasket is manufactured in house to exceptional tolerances, unlike the OE and aftermarket products which protrude out the casing. All gaskets are made from scanned vector mapped images of the OE casing to ensure an exact fit, the gasket material is high-quality BS7531 GRADE X with a working temperature up to 250 degrees centigrade. This gasket is similar in dimensions and looks to the original part number 31140-422-000. This fits all CBX with the larger US style alternator. The diameter of the US alternator is 150mm so you can identify your alternator from measuring this diameter.