Installing a fantastic vent on the roof of your RV is a pretty simple job when replacing an existing vent with 12 volt wiring nearby.  First, you will need to remove the inside vent garnish. This is normally fastened to the ceiling with 4 screws.  Remove the screws and remove the garnish.  Next, you will need to disconnect any wiring to the existing vent if it has a fan in it already.  Now you will have to get up on the roof and scrape the caulk away from the screws that are around the perimeter of the vent flange.  Once the screws are removed carefully insert a putty knife in between the vent flange and the roof material and gently pry up on the vent.  Be careful not to pull to hard on the vent as you risk tearing the roof material.  Once the vent is removed clean the existing caulk and putty or butyl tape material from around the perimeter of the 14 x 14 opening in the roof. Once the area is cleaned you are ready to install your Fantastic vent.  You will need to apply new putty or butyl tape around the flange of the vent then insert the vent into the center of the opening in the roof.  Next, fasten it to the roof by installing screws into the existing holes in the Fantastic Vent.  Once the vent has been fastened to the roof, caulk all screw heads and around the perimeter of the vent with rubber roof caulk (for rubber roofs) or latex caulk for others. Now its time to finish the interior. If the previous vent was wired, simply use the existing 2 wires and connect them to the new Fantastic vent. If not, you will have to find a 12 volt DC source. In most cases, there is usually a ceiling light nearby that you can tap into making sure that the light is not operated by a wall switch. Remember to not reverse the polarity. If you have one red and one white wire, red will be + and white will be -. If you have one black and one white wire, black will be + and white will be -. If you have one red and one black wire, red will be + and black will be -. You can connect these to the cooresponding wires on your new vent.  Once that is connected it is time to install the garnish by raising to the ceiling and fastening it with the 4 screws previously removed from the old vent.    Thats it your done and can sit back and enjoy the fantastic air circulation your new vent provides!