Introducing the VTi, Visual Temperature Indicator. Instant and continuous high temperature monitoring in real-time. The Visual Temperature Indicator (VTi) is a wearable thermoreactive technology which offers immediate, accurate and continuous temperature monitoring for everyone. The VTi helps protect families, businesses, institutions and healthcare settings, providing an added layer of protection in a simple and cost-effective way. In a complicated world the little things that will bring us back together..