Disc Brake Rotor Gauge Set 0-1″/0.001mm Ball Joint Runout Gauge Set with 13.77″ Flexible Arm and 7″ Tight Grip Locking Plier,Widely Used in Automotive Maintenance and Industrial Processes. Disc brake rotor gauge can help you check tire and wheel run-out, gear backlash and valve guide wear to improve your driving safety.