for the cat l1 are these s2 material 4.0mm thick front and rear shock mounts. designed for carpet astroturf and clay these mounts lower the centre of gravity by mounting the shocks lower and in turn giving more droop. the team have found this helps with taking off and landing big jumps and also helps with bump handling. the bump and jump handling is due to the design and a new composite material which introduces more flex in the towers which help the cat l1. when the towers are installed you will need to remove the o-rings on your front shock shafts and run only one on the rear.