BlueSpot 8 Piece Brake Pad Thickness GaugeIdeal for the Quick and Easy Confirmation of the Road Worthiness of Brake Linings without the Need for Removing PartsThe Offset Gauge is Inserted Between Brake Disc and Pad, the Blade which Sits Most Snug is Indicative of the Wear on the PadThe Set Includes 3 Colours which Denote the WearRed must be Replaced Immediately - Yellow Pad is Becoming Worn - Green Pad is in Good Working OrderThe Gauges are Additionally Marked with the Metric Conversion for the Offset: Red: 2mm and 3mm - Yellow: 4mm, 5mm and 6mm - Green: 8mm, 10mm and 12mm