HANGER BAR SET: 4-piece set holds your InVent series fan securely STURDY: Bar set help ensure a custom fit with exact positioning to securely hold your fan DURABLE: Constructed of durable steel for long lasting use ADJUSTABLE: Hanger bars are adjustable for maximum flexibility and can be used with either 16" or 24" on center joists EASY INSTALLATION: Hanger bars make setting up and installing your InVent series fan easy with the 4 included mounting screws!