How to determine piston style and size:
All seal and boot dimensions are determined by the piston diameter, but must note whether you have external or internal fit boots.
Why RB Stainless Steel Piston (vs. Aluminum):
1. Much lower in heat transmittal, only about 10% of aluminum = Less brake fluid replacement.
2. Better dimensional stability (Lower heat expansion rate) = Better rigidity in brake torque transmittal.
3. Detail machining & thin wall cut with chrome plate on surface.