The 9 Piece Manual Brake Gauge Set Allows Brake Pad Wear to be Accurately and Consistently Measured without Guessing. Designed to check both straight on or at a 90 Deg. angle to the rotor with offset tips so the gauges can be used without removing the wheel or caliper assembly on many applications. Brake lining gauges identify thickness levels for brake lining inspection. Made from durable, flexible acetal. The gauges are color coded to match SAE or Metric recommendations for brake pad replacement.