Light Kit for Cat® D11 Bulldozer #42131 (Upgrade Ver.)Supports already built LEGO sets with a little refitting required. No circuit experience needed, just follow our simple step by step instructions for guidance. Twisted pair design balances robustness and installation concealment. Have your LEGO sets be exciting and soul filled even in the daytime. Two Versions: Both of Classic and RC Versions with the same quantity of lights. A more fun way is RC Version includes a RF controller( about 10 M control)