Features Aluminum Material: Gauge inside caliper is made of aluminum alloy material with exquisite craftsmanship, wear resistant and practical, which can be used stably. 10 Replacement Heads: The gauge inside internal caliper kit contains ten interchangeable internal caliper heads with different ranges and specifications for you to use according to the actual situation. Clear and Easy to Read: Our gauge inside caliper pointer readings are clear and easy to read, with longer life and high accuracy to help you minimize measurement errors. Specifications and Measuring Depth: Gauge inside caliper is available in 55‑153mm or 2.2‑6in with a reading of 0.01mm and a measuring depth of 90mm or 3.5in. Widely Used: Our inside caliper is widely used for the measurement of all kinds of bore, inside diameter, inside groove size. Specification: Item Type: Gauge Internal Caliper  Material: Aluminum Alloy Specification: Approx. 55-153mm/2.2-6in Reading Value: 0.01mm Error: ±0.02mm Measuring Depth: Approx. 90mm/3.5in Use: Widely used in all kinds of internal holes, internal diameter, internal groove size measurement Package List: 1 x Gauge Dial Inside Caliper 2 x Wrench 10 x Gauge Dial Inside Caliper Head 1 x Manual 1 x Storage Box Package List 1 x Gauge Dial Inside Caliper 2 x Wrench 10 x Gauge Dial Inside Caliper Head 1 x Manual 1 x Storage Box