From memory, Euro Car Parts who are one of the UK's largest suppliers to the non-franchised garage trade, control and possibly own the Circoli brand. In this type of arrangement there is some chance that Euro are sourcing from OEM suppliers whose contracts preclude them from participating against the OEM in the aftermarket. Equally, some parts could be sourced from 3rd party suppliers who clone OEM designs. I'd speculate that the motor trade at large would not endorse fitting of Circoli parts if there was a high failure rate, as the trade would have to cover the labour content of repairs. The INA belt is made by a major OEM supplier Schaeffler who own the brand, and it will probably be a re-badged OEM part.