The 2054295, OMI-300P-5 Mahr Snap Gage 4-5"/102-127mm Range (without indicator) is on sale at Gaging.com LLC.  The 300P snap gage are excellect for highly accurate, repeatable results.

• Patented “Channel Lock” design assures parallel anvil surfaces throughout the full 25 mm / 1“ range of adjustment
• Fully adjustable with positive position locking at any point within the range
• 0.50 mm / .020“ Range of Sensitive Contact
• wide range of sizes, styles, and indicator configurations
• 15.5 mm / .61“ square tungsten carbide anvils are flat and parallel to provide long lasting working surfaces
• Indicator can be turned to read from front or rear of the gage
• Optional lift-lever model (301P) available for retracting the upper anvil
• All adjustments performed using a single alan wrench (supplied)