The probes that come with Range Dial are safe to use in your oven as long as the temperature in your oven is below 450º/230ºC. The Dial itself contains electronics, batteries and meltable materials, so leave that on your counter or use the magnetic base to stick it to your fridge or stove (just not too close to the heat).

Stick the probe in your roast, thread the cable through your oven door, and close the door on the cable. Your oven's door has a rubber gasket that will seal nicely around the cable — it won't damage it or let any heat escape.