8421 Mobile Crane is a TECHNIC set released in 2005 as part of the TECHNIC line. With 1884 pieces, it is the second-largest TECHNIC set pieceswise, with the new 8110 Mercedes-Benz Unimog U 400 having 2049 pieces. It builds into a large, yellow, crane truck with both pneumatics and motorization to work the boom and winch. It includes instructions for the alternate model, which is a cool bucket truck. It's recommended for children aged 11 through to 16.