Fowler-Bowers XTD3 Digital Internal Micrometer These bore gages have been designed to further simplify the accurate measurement of bores. All XT instruments offer fixed anvils. Sizes above 1"/25mm offer extended travel. They are available as individual instruments or in complete sets. Package includes the following... Measuring Head Display Handle Setting Ring Features include... 4-5" / 100-125mm Measuring Range 0.00005" / 0.001mm Resolution 4.53" Measuring Depth Large easy-to-read display.