All BHJ SFI-certified harmonic dampers have a serial number engraved on the damper. This serial number matches the official SFI certificate letter that is included with every SFI harmonic damper when purchased.
The SFI certificate is shown to tech inspection at the racing facility and matched to the serial number on the harmonic damper for verification.
If a SFI certificate has been misplaced, a replacement SFI certificate letter may be purchased, by clicking here.