The Search Sub is way cool! It incorporates the pnumatic air tank so you can store the air until it's needed. With other pnumatic sets, you move the switch and pump the air. The model performes the action. With this, pump air into the tank and when you want the claw to open or close, move the switch. You can continue this for about 7 opens and closes before you have to pump more air. Besides, the air tank looks nice on a sub!
On the roof of the sub, right over the air tank, is a grey Technic steering wheel. Turn it to open and close the cockpit door which is made of yellow flexable tubes, like many Technic sets. Now the diver can come out on a mini vehicle that you can attach a drill to. In the front of the ship is a big black claw. You know those transparent blue halves that make lasers in the Exploriens theme? Four are here in yellow. Two are made to make a barrel for the claw to lift and the others are part of the ship.
This set comes with a whopping 18 stickers! You actually put stickers on the tech figs legs. Oh, and about that figure. He has the head with dark eyebrows and lines under his eyes that are pretty rare. He's complete with diving gear. Fins air tank and mask (not helmet). There is actually a very small piece of pnumatic tubeing running from the air tank to the mask. I love Lego for doing this!
The ship almost all yellow. If you have this set, some ideas are to put a battery box inside the back. Run a Lego wire from it to the front to a train light placed near one of the lights on the mini vehicle. The only place I know where to get long wiring is from the Metroliner (although I'm sure other trains have them) and the Space Shuttle. The Space Shuttle has wiring 3 times as long as the entire sub. If you have never tried pnumatic, enjoy Technic figs, and want a lot of Technic special pieces, this is for you.
Oops! Forgot the alternate. It's a base with a wheel to turn a crane. Use the pnumatics to lift an lower the crane. There is also an exploration vehicle. It's worth building, but stick with sub. The alternates functions are awkward.