6-100mm Three Point Internal Micrometer with Setting Rings
Measurement can be taken closer to the bottom of the blind bore, and can be taken into a deep hole with an extension rod.
Highly durable because of carbide-tipped contact points.
Within 12mm/0.5": 0.001mm/0.0001"
Over 12mm/0.5": 0.005mm/0.0002"