This is a Mitutoyo digital thickness gauge, model 547-301, used for precise measurements of thin materials [547-301].
It features a digital LCD display with a measuring range of 0-12.7mm (0-0.5 inches) and a resolution of 0.01mm (0.0005 inches).
The tool includes a thumb trigger for easy operation and is designed to measure thickness of materials such as paper, film, or leather.