Clutch set off of an RX1 , they have the Bender Racing Heel Clicker clutch kit installed , we're off a stock RX1 used between 0-2000' elevation , will work on an Apex or Nytro also ! The Heel Clicker weights are fully adjustable ! Clutch kit was installed in 2012 and has about 1000mi since , clutchs were rebuilt then also ! These are complete and ready to bolt on !