The Westinghouse Fan Master Jr. Non-Metallic Support Box allows you to safely and securely attach a lighting fixture or ceiling fan to a building's structural support. The fixture or ceiling fan is supported by the joist, not the box. Perfect for new construction, the Fan Master Jr. can be used in applications where duct work or wiring is present. The design features 13.4 cu. in. wiring capacity on only one side of the box, so the Fan Master Jr. can be installed on either side of a joist without having to split the wiring. It includes two knockouts for conduit or Romex, one Romex connector and one Romex clamp. The Fan Master Jr. is UL listed for fixture support of 150 lbs. or less and ceiling fan support of 70 lbs. or less. The box works with any model of ceiling fan and has a two-hour fire rating. Fan Master Jr. can be mounted on standard joists as well as wider joist configurations where a saddle style box will not fit. Product reference number 02525.