Glossary
IP rating
A two-character code stating how well a device resists solid particles and water, for example IP54 or IPX4.
An IP rating, short for Ingress Protection, is a standardised code describing how well a sealed device keeps out solids and liquids. It is written as IP followed by two characters: the first for solids such as dust, the second for water. IP54 means limited dust protection and resistance to water splashed from any direction. An X in either position means that property was not rated, so IPX4 makes the same splash claim as IP54 while saying nothing about dust.
What it does not promise
The water figures describe splashes, rain and sweat. Nothing in the range used by eyewear covers immersion, so a rated frame is protected against being caught in a downpour and is not protected against being worn in a pool or a shower. Ratings are also measured on a new device with fresh seals, and they degrade with age, heat and impact rather than lasting for the life of the product.