There's lots on the market - I've got a NexXtech but depending on all the features you want there's other brands that can do more. Mine gives me indoor/outdoor, time, alarm & the option of 3 outdoor sensors.
That means I can put one sensor inside the trailer, one inside the fridge (I suppose) and one in my backyard to monitor temps from the mobile base station in the house. The sensors all transmit wirelessly, so when we travel, I could mount one of the outdoor sensors outside the trailer and take the base station with me....
Not sure how well the sensor in a fridge would transmit its data but hey, worth a try!
3 kids and Buddy the Dog;)
2010 JayFeather 23K
05 GMC Envoy XL