Ready for speed? Ready for impact? It’s time for the 42072 LEGO® Technic WHACK! with awesome pull-back power and outstanding acceleration. Also features a sturdy front bumper, large rear spoiler and wide black rims with low profile tires and an engine pop-out function which is activated on impact. Combines with the LEGO Technic BASH! pull-back to create an awesome WHACK! ‘N’ BASH! combi model with two pull-back engines.Also, get a glimpse of the design process and the challenge of designing the pop-out engine with LEGO Technic Designer Samuel Tacchi.