- This 6 piece set is ideal for measuring inside of guides, guide bores, cylinders, etc.
- Size range: 5/16" to 6"
- Compress the spring plunger and lock by twisting the handle
- Insert into bore and release the plunger; it will expand to fit
- Lock it again and remove then measure the size with a micrometer
- Double plunger design for consistent measuring
- Long lasting finish with a handy storage case