The distinctive VTi cross design is two different sizes and thicknesses. The thermochromic green cross is thicker and covers the red when a temperature is normal. When a temperature rises above 37.5c the thermochromic reaction takes place and reveals the red cross that is significantly finer than the thicker green cross.
We understand this means a person that is colour blind would need to spend time to familiarise themselves with the differences in sizes. This is not ideal, and we acknowledge there is more that can be done to improve the VTi for people with sight challenges. This will not stop the wearer of a VTi being supported by others if their VTi changes colour, but we fully understand that a person that is colour blind might have difficulties helping others.
In time we will be looking to introduce different variations of the VTi.