The biggest problem with these plastic pieces is usually not the deterioration of the plastic, but the fact that there are a couple of screws hidden up under the rear window weatherstrip! The holes for the screws are really close to the edge of the piece, and in the case of the hole nearest the middle of the car, any careless installer on the line (which was just about every installer) would run the screw into the piece too tight and cause the plastic to crack! Once the car hit a few bumps, the crack develops into a break, and even if it's not broken, getting the screws out to remove the piece almost always results in breaking the corner off! I have at least 3 sets here, all with broken corners on them, and don't even bother selling those, figuring everybody has broken ones!! To get an unbroken one out of the car intact is a lesson in patience and care!!