Topping the list of items flagged for Customs detainment or seizure are so-called “HID kits”, which place a Xenon burner in headlamps meant to take a tungsten-halogen bulb. NHTSA’s lighting enforcement chief Mike Cole says it’s understandable that people want to update their cars’ lighting, but “’HID kits’ endanger traffic safety; they cause headlamps to distribute the light incorrectly and produce dangerous levels of glare.”
The agency’s compliance-enforcement staff has been augmented, and U.S. Customs has a frequently-updated list of offshore companies known or suspected to make “HID kits”.