Audio Designs & Custom Graphics machines the Chevy Impala Speaker Adapters on our in house CNC machine. This ensures a perfect fit EVERY time. This is a complete set that includes tweeter, front door, and rear door adapters. By bringing the speaker out and adding a FAST Ring, it seals the speaker to the back side of the door to force all the acoustic energy directly out of the door panel and does not trap it between the door panel and door. Sealing it up significantly increases your midbass response and increases the sound quality of the speaker as a whole. Our speaker adapters are machined out of Expanded PVC vs. wood, so they will not swell up, take on water or expand like wood rings would. They are also stiff so they will not vibrate and that helps out with the midbass response. With us cutting the adapters, your speakers will fit perfectly. They are spaced out so you can fit a deeper midbass driver.