Thermometers for high temperature ovens
You'll want a commercial oven or high heat thermometer.

This one goes to 750&deg; F (about 400 C):



My Big Green Egg Temperature Gauge goes up to 750&deg; F (about 400 C).



But if I want to monitor the internal temperature of what you are cooking in a hotter oven/broiler, I usually use a remote thermometer which has an all-metal wire and probe: