Known as 'Squiddies' to the rebels, Sentinels are machines designed for search and destroy. Sentinels search out rebel ships to swarm them and tear them apart. Rebel ships power down when sentinels are near so they can use an EMP (Electro-Magnetic Pulse) to attack them if the ship is spotted. The sentinels formed an army to wipe out Zion, using Diggers to drill down into the ground. Some sentinels are equipped with bombs, which they can launch at a ship while staying out of EMP range.
This thing is superbly built! My only problem is the fact that you had to paint the wheels, but I think the sheer coolness of this MOC made up for that bit. Lego should make those wheels in black too y'know... unless matrix had albino sentinels :-P