The clear plastic part houses the LED assembly snaps over the tubing and is sealed to the tubing all the way around with a squished layer of silicone. You can see if it seals. Then the metal cover snaps in place and is screwed down. The clear plastic is visible all the way around the metal cover (it's the same size) and light gets out around the edges, which is cool. The clear part sticks out past the metal by about 1/8" or so, adding to side visibility.