To allow for expansion and contraction in a run of rigid metal conduit; For applications involving IMC a 15 IN minimum length of rigid conduit should be used entering the expansion fitting due to the slightly smaller outer diameter of the IMC; Weatherproof
Standard:
Third Party Certification: UL File Number E-11853 Per NEC 250.98, CSA 11584, Applicable Third Party Standards: UL 541B, CSA C22.2 No.18, Federal Specification W-F-408E, NEMA : FB-1