For more than 25 years, Guardian Fire Testing Laboratories, Inc. has been a leader in fire testing, field labeling, product certification and factory inspections. We are accredited as a Product Certification Body (Listing & Labeling), as a Testing Laboratory and as a Third-Party Inspection Agency. Guardian’s Signature Services: Field Labeling Evaluation: On-site evaluations and re-labeling of door assemblies that are missing fire labels. Specialty Door Program: fire rating for oversized and one-of-a-kind doors Product Certification: Listing and labeling services for test standards and code compliance for steel doors and frames, mineral core doors, wood core doors and frames and other building materials.