Feeler gauges, calipers, micrometers, and dial indicators are used to obtain very precise measurements. These tools can provide measurements to the nearest thousandths (0.001) of an inch or to the nearest hundredths (0.01) of a millimeter.
Feeler Gauge. Feeler gauges consist of flat metal blades that are a specific thickness. You can put several feeler blades together to obtain a desired thickness.
Caliper. A caliper is an especially versatile measuring tool able to measure inside, outside, and depth dimensions. However, when extremely precise measurements are required consider using a micrometer.
Micrometer. Micrometers are particularly good for measuring the diameter of objects.