Brembo GP4-RS Caliper vs Brembo GP4-RX Radial Caliper Kit

Both are 108mm radial four-piston Brembo calipers for sportbikes, but they are built differently. The GP4-RS is a cast monoblock with MotoGP-style cooling fins, about 10% lighter than the M4 One-Piece, and aimed at track days and hard road use. The GP4-RX is a CNC-milled two-part caliper with 32mm pistons, a nickel finish and TÜV/KBA approval on many models, so it suits riders who need street legality and easier servicing. Owners praise both for strong, precise braking; pick the RS for track focus and the RX for road legality and rebuildability.

• Choose the GP4-RS if you ride track days and want a lighter, finned monoblock caliper with 30mm pistons and sintered pads in the box.
• Choose the GP4-RX if you need street approval, a CNC-milled two-part body and 32mm pistons for stronger initial bite on a road-and-track bike.