This transformer is a universal replacement for many gas and electric furnace models. The two foot mounting holes are spaced 3-1/8" on center. There are six wire leads which have tinned ends. The blue and yellow leads are the 24 volt supply to the low voltage control system. On the line voltage side the black wire is common and is connected for all incoming voltages. Connect the white wire for 120 volts, the red wire for 208 volts, or the orange wire for 240 volts. Cap or insulate the unused primary leads.This part is covered by the exclusive Protactor two year limited replacement policy. If this part fails within two years from date of purchase, return the defective part and a copy of the original invoice to the place of purchase for replacement. Contact the authorized Protactor dealer that you purchased the part from for details. Original equipment manufacturer's brand name(s) and part numbers are used for identification purposes only. This item is supplied by OneTrip Parts and meets or exceeds original equipment specifications.