Vertical flywheels are a type of heavy rotating weapon which first became prominent in later series of Robot Wars. The first robot to be equipped with such a weapon was Daisy Chopper in Series 3, while the most successful UK series competitors to be equipped with one include the Series 7 version of X-Terminator, which finished fourth in that series, Series 5-6 Semi-Finalist S3 and joint Battle of the Stars champion Kadeena Machina. House Robot Matilda was also equipped with a rear-mounted vertical flywheel from Series 5/Extreme 1 onwards, replacing her chainsaw in the UK series and being made interchangeable with it in Robot Wars: Extreme Warriors and Nickelodeon Robot Wars.