It shall be an unfair or deceptive practice for a handgun-purveyor to transfer or offer to transfer to any customer located within the Commonwealth any handgun on which the serial . number has been placed solely in a location on the handgun that results in the number's susceptibility to eradication. A serial number shall be deemed not susceptible to eradication for purposes of 940 CMR 16.00 if:

( 1) it is placed on the interior of the handgun, and the handgun-purveyor provides information regarding the location of the interior serial number to the Office of the Attorney General and other law enforcement officials upon request; or

1. (2) it is placed on the exterior of the handgun in a way that is not visible to the unaided eye, but is visible with the aid of an infrared detector or other device, and the handgun-purveyor provides information regarding the location of the non visible serial number or any method by which this number can be made viewable to the Office of the Attorney General and other law enforcement officials upon request.