Gauge block holders and jaws keep gauge blocks securely in place. Other gauge block accessories are used to secure and position blocks for specific applications. Height gauge checkers and caliper checkers are constructed from steel gauge blocks aligned on a solid frame, allowing the operator to confirm that a dial, digital or vernier caliper or vernier or digital height gauge is within tolerance at a range of positions. Probe compensation blocks can be used to calibrate and zero-set height gauge probes and scribers of different sizes.