Are listed and labeled by Underwriters Laboratories, Inc. according to UL 752 standards. UL listed products are certified by UL to meet standards as tested in their facility. Additionally, UL listed products are subject to UL’s follow up service with periodic factory inspections to ensure that products do not vary from the original design as tested and listed by UL. Each UL listed assembly has a label affixed to the protected side that includes the UL file number. Beware of companies that provide products that ‘meet’ UL 752 standards, without the UL label there is no guarantee that even the manufacturer has ballistically tested the assembly.