Source for temperature probes for meat smoker

I'm guessing someone here may know of where I can find (most any type) probes like are commonly used for meat thermometers. Should be waterproof and pointed to stick in a roast.

I'm thinking it is time to upgrade my smoker to say four probes and wifi based, but haven't seen any good probes.
TIA

The probes for RediCheck are available as spare parts