Defining filters for original and compatible is tricky. The filters considered to be original, therefore belonging to the machine's brand, are actually produced by other companies and are simply labeled. An example could be the Mann Filter separator, is labeled with compressor brands and considered to be original. In this case the filter is produced and patented only by Mann Filter, so Mann Filter should be considered the original brand.
SF-Filter always offers the best solution, ensuring that you receive high-quality products without the high price of an 'original' brand.