Jeep Grand Cherokee WJ - Roof rack cross bars:
"The rail end caps, two at the rear and two at the front, are attached with plastic clip tabs. To remove or install the adjustable crossrails, the two rear caps must be removed. The easiest way to remove them is to pry out one side with a trim stick or your fingers while pulling the cap up from the back (front side of vehicle). Note the location of the lock tabs in the photo above. The edges of the caps can be sharp so it's best to use a rag or glove to protect your fingers while pulling them off. When re-installing, make sure to align the end tab and check that they are completely seated on all sides."