The GNX4 Brake Kit is the product of Wilwood's in-house FEA design and 3-D modeling technology. The GNX4 caliper paired with 12.00" diameter, .95" width rotors offers a durable, high torque braking solution. This is the current upgrade for AM General Military REV HUMVEE vehicles and will require modifications to vehicle platform for installation. The GNX4 caliper with its unyielding strength and superior piston design generates positive pedal response and high clamping efficiency with a substantial weight savings over original calipers. The caliper feature a natural aluminum finish protected by a durable clear coat anodizing. Forged billet aluminum bodies, stainless steel pistons, and high-temperature seals put an end to the rust, bore pitting, and seal failures that plague many OE caliper design. Stainless steel pistons delay the heat transfer from the pads while the aluminum calipers dissipate the heat quicker than the OE cast iron calipers. Cooler operating temperatures translate into longer service life, regardless of the driving environment. Note: rear kits do not come with provision for parking brake.