"This was my first Technic set. What a delight! Moving pistons in the engine and spinning fan. Gear system for steering. Gear system for opening and closing the jaws. Lever mechanism for raising the barrel. The movement of the finished model is smooth. It was lots of fun to build and a great intoduction to technic. The instructions were easy to follow and detailed. Instructions also included for the alternative build. Nice kit Lego."