These parts were created for 2 main purposes:

1. To have the FF01 accept shorty LiPo's. Inside the chassis you need to shave away some plastic so the LiPo can pass. The adapters left and right are a bit loose, but that isn't really an issue. You need an M3 screw in the chassis adapter and a self locking M3 nut to fix the top battery holder.

2. To change the suspension a bit in the rear. You need really long dampers in the rear. With this new part you can mount the dampers a bit lower and you can change the angle: there are 2 mounting positions.

There is also a rear body stabilizer.

These parts might also fit a TA02 chassis.