I recently had to rebuild the front and rear brake calipers on my 1999 Kawasaki ZRX1100. Although both the front and rear brake calipers were working, they were also dragging. Upon disassembly of the calipers, there was corrosion under the piston and dust seals which affected the pistons from retracting. The Brakecrafters kits for rebuilding the front and rear calipers provides everything you need to rebuild the calipers. It even includes special grease for the seals to prevent damage when installing the pistons. Will be ordering rebuild kits from Brakecrafters when I need to rebuild the calipers on my other bikes.