Reflex glass generally reflects light that comes in from the outside. It often has grooves shaped at 45° angles, enabling a light wave to pass into a liquid or gas chamber where its speed changes, resulting in a shift in direction. Grooves in reflex glass can have reflecting prisms etched in, which can break the light wave up into its parts. Often used in scientific instruments, reflex gauge glass helps to determine the liquid or gas content in a sample based on the reflection and refraction of light that passes through.

Reflex glass generally reflects light that comes in from the outside. It often has grooves shaped at 45° angles, enabling a light wave to pass into a liquid or gas chamber where its speed changes, resulting in a shift in direction. Grooves in reflex glass can have reflecting prisms etched in, which can break the light wave up into its parts. Often used in scientific instruments, reflex gauge glass helps to determine the liquid or gas content in a sample based on the reflection and refraction of light that passes through.