They laser engrave lettering into the X2 ND traction frame to ensure that the lettering won’t ever fade or come off after consistent use. They also engrave each and every X2 traction frame with a unique serial number.
When you activate your 25 Year Ironclad Guarantee online they associate your X2 serial number to you, so any future discussions on this unique filter are tracked, issues recorded and all that stuff which goes into future product design.