The Faithfull Feeler Gauge contains 20 blades that cover the sizes from 0.05mm to 1.00mm. The blades are 100mm long and made from hardened, tempered and polished steel. A knurled thumbscrew allows the blades to be locked in place. Feeler gauges are used to measure the size of small gaps between 2 objects that are in close proximity. Ideal for setting gaps between components in vehicle engines such as valve adjustment, setting distributors and checking spark plugs. Ref: UTTK9659