Starrett 121AZ Long Range Tubular Vernier Inside Micrometer Set, 32-57" Range, 0.001" Graduation, +0.0004"/-0.0000" Accuracy

Tubular inside micrometers are designed for large internal measurements beyond the capacity of most other micrometers. Each set consists of a micrometer head mounted at the end of a tubular holder in which measuring rods can be inserted and adjusted to the desired size. Final size reading in thousandths of an inch (0.001") is obtained using the micrometer head. Rods and holder are made of steel tubing, light in weight, yet very rigid. Each rod is accurately graduated with inch divisions, which are set to the size desired by a line on the holder, and firmly held by a large, knurled clamping nut. The collet has a design, insuring an extremely tight grip on the rods at any setting. Movement of screw: 1".