OEM stands for Original Equipment Manufacturer, and it refers to parts that are branded with the automakers name and/or logo and come in the automakers packaging. OEM parts are built with high-quality materials and to the automakers specifications, and they are considered by many to be the best choice. Contrary to popular belief, most OEM parts arent made by the automaker but rather a third-party contract manufacturer. OEM parts are known for being more expensive than aftermarket options, but they are generally of higher quality. Aftermarket parts, on the other hand, are made and branded by a third-party manufacturer and dont have the automakers name branded on them. Aftermarket parts vary widely in quality and fitment, and some manufacturers offer inexpensive alternatives, while others try to surpass OEM quality. Its important to proceed with caution when considering aftermarket options, as many manufacturers claim that their parts are OEM-quality, but its difficult to know if youre actually buying an OEM-quality replacement part. In summary, OEM quality refers to parts that are built to the automakers specifications and are considered to be of higher quality than aftermarket options.