The panels shown are made of 1/4" MDF, 1/2" MDF and fiberglass. They mount up to the stock mounting holes that the stock speaker assembly mounted to.
You remove the factory grills and front mount your speakers to the actual inside door panel.
The new panels allow for a secure place for the speaker to be screwed to.
Also... It is very important to completely sound dampen the ENTIRE door. Because of the differences in elevation with the stock speaker assembly screws you will have "fill" in the area between the arms of the panel with sound deadening. You want the speaker to play in as close to an enclosure as you can simulate. Doing this will greatly enhance your mid-bass resonse.
Questions??? Email me privately.
San Antonio, Texas