Abstract: In a disk drive enclosure system having carriers fitting into slots in the enclosure, each carrier has a lock mechanism. The lock mechanism has a part which rotates between locked and unlocked positions, and the part has a feature that blocks removal of the carrier when the part is in the locked position, while permitting removal of the carrier when the part is in the unlocked position. The part is plastic and is molded of a clear material serving as a light pipe. A light source is behind the part, so that the ability of light to pass through the part is affected by the locked/unlocked position of the part. The part has a shape feature that assists a user in distinguishing between locked and unlocked positions, and the light indicator further assists the user in this way. Valuable bezel space is saved, especially in comparison with some prior-art locking mechanisms.