Celebrate a hero of the construction world as you build a replica version of the biggest Cat® dozer with this LEGO® Technic™ App-Controlled Cat® D11 Bulldozer (42131) kit. This large set lets adults enjoy quality ‘me time' focusing on their passion. Just like the real Cat® bulldozer, this model is built in modular sections. LEGO fans will love the new-for-October-2021 LEGO element – a large track that can be tightened and loosened. And the build is just the start! With many authentic features and functions packed into this model, there's lots to discover. Take control of your bulldozer model Use the CONTROL+ app to operate and explore this heavy-duty machine. Use the app to drive and steer. The app delivers realistic movement as you raise, lower and tilt the blade or raise and lower the ripper and ladder. Explore engineering LEGO Technic buildable models feature realistic movement and mechanisms that let LEGO builders explore engineering concepts in an approachable and realistic way.