CFR › Title 46 › Part 164 › §164.018-346 CFR §164.018-3Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkThe following types of retroreflective material are approved under this specification:(a)Type I—Material used on flexible surfaces and rigid surfaces, except rigid surfaces that are continuously exposed.(b)Type II—Weather resistant material used on continuously exposed rigid surfaces.