You don't use a micrometer to measure with a small-hole gauge. A small-hole gauge is a specialized tool designed for directly measuring the inside diameter of holes.

Here's how you use a small-hole gauge:

1. Select the appropriate gauge: Each gauge has a specific size marked on it. Choose the gauge that best matches the size of the hole you want to measure.

2. Insert the gauge: Gently insert the gauge into the hole.

3. Check for fit: If the gauge fits snugly, without any binding or excessive looseness, then the hole size matches the gauge's size.

4. Note the size: The size of the hole is the same as the size marked on the gauge.

Micrometers are used for measuring the outside diameter of objects or the thickness of materials.

Here's why you wouldn't use a micrometer with a small-hole gauge:

* Accessibility: Micrometers are designed to measure the outer surface of objects. They wouldn't fit inside a small hole.

* Accuracy: Small-hole gauges are specifically designed for measuring inside diameters with high accuracy. Using a micrometer would not provide the same level of precision.

Let me know if you have any other questions about measuring tools!