The Mechanical Blowfish. Using a crank and linkage rod system this robo-fish propels itself through the water by its swinging tail fin. White under-belly holds the motor, gearbox, battery box and switch and is sealed water-proof tight. Parts are easily put together by snap-lock pieces or screws, and transparent green back means you can see all the mechanics even after completion. Gearbox transfers motor rotation to swinging tail movement via crank and link rod. The gearbox plays the vital role of reducing motor speed, allowing for splash free movement. Takes about 7 seconds to swim 1 meter. Uses water proof taping and rubber O-rings to stop water coming in through screw holes, power switch, tail fin and joining line between top and bottom halves. Pull the stopper located at the base of the tail and turn left or right to control the swimming direction. The more you turn the stopper the greater the change in swimming angle. The tail is also made from an easy to cut material, allowing you to freely shape the tail for best swimming performance.