INDOOR | Cover for Single Receptacle 1-13/32 in Dia, for 4 1/8 X 2 3/8 in Boxes | Reusable Ferrule. Long Ferrule Prevents Pullout and Tight Bend Conduit Pop-Out. Furnished With Locknut and Sealing Ring | Use Through Knockout to Connect Box to Conduit Coupling; Use With a Locknut to Connect Two Boxes Side by Side or Back to Back; Use With a Locknut to Connect Fixture Housings in Continuous Runs; Rigid Conduit Threads (Nps)Furbay Electric Supp