Typically used in combination with a flat reference tool such as a straightedge or a surface plate, a feeler gauge is used as a variable go/no-go gauge to determine how much a surface is out of true. It is also handy when gauging precise offset measurements such as when adjusting plunge stops, fences, or planer knives.
The fingers of a standard set are often too short; these 1/2" wide by 5 1/2" long gauges are ideal, allowing you to reach into a space and still see what you are doing. The extra length also lets you use built-up combinations (e.g., 0.025" + 0.016") without distortional error. From 0.001" to 0.025" (accurate to a quarter thou!).
Polished tempered steel. Made in USA.