45-degree fitting that is doubled up to form a 90-degree elbow where required. Used for tight radius duct transitions to ensure optimum airflow. UL 181C and UL2043 certified as part of a connector assembly. Complies with Standard UL2043 and is identified as Classified with the ETL listed mark, control number 5016806. Complies with Standard UL181C and is identified as Certified with the UL listing mark, file number MH64419. PC/ABS UL94 V-0