The Direct Fit Van Windows for Sprinter, Transit and Promaster Van's,  utilizes factory metal stamping; on Van's interior, you will notice an area where the inner metal ends. Here is a photo to clarify. You will cut right along with that edge around. Also, your Van may have multiple uprights. You will cut those out straight with your opening.

When replacing an existing factory window, you may want to contact us or provide photos inside and out. Not all replacements will be straightforward and require extra commendation and custom adaptation to use an existing factory or add-on item(s). Van Windows Direct and the manufacturers we distribute take no responsibility for additional work or an installer's inability to complete the work required. Please ask all questions and provide all information before purchase, as the buyer is 100% responsible for the installation or failure to install. 

If replacing an existing factory Sprinter Van window glued in, you may want to take it to a professional for removal and replacement. The best tool to use is a wire cutter  Equalizer Window Cut-Out Set. Once the Window is cut out, you will need to cut the original urethane down as flat as possible and clean as much away as possible with CRL Adhesive Cleaner. 

Once the Hole has been cut or your original window removed, it's time to install the new Window. 

The CRL Window utilizes a trim ring (clamp ring) installation. Before putting the Window on the Van, it's best to go through and make a small pilot hole in all the locations around the trim ring. That way, you do not get around the heads of the screws when tightening the Window. 

Put the Window in place from the outside of the Van, allowing the aluminum mounting frame to extend through the Hole in the wall. Next, place the clamp ring from the inside. Most vans will have the split on the bottom. With one person holding the Window in place on the outside, the other can start the screws from the inside. Generally, begin with the two at the split in the trim ring to have that lined up, then top and around. You do not want to tighten once all screws are in place; you can go back around and pull them. Be sure to tighten evenly around for proper seal.