"The Maze 4 features a laser cut removable Lucite top. Such a clear top provides several benefits. The first benefit is easy accessibility for cleaning, and the second benefit is the ability to view the block for contaminants. The Maze 4 is sealed with a replaceable rubber o-ring; Danger Den sells extras as an inexpensive addition. Lastly, our blocks were outfitted with the chrome barbs..."
FULL STORY @ NEXUSHARDWARE (http://nexushardware.com/articles/index.php?id=18)