WE think you should buy at least two.. but if you just want one that is ok. As you know the CDN thermometers are great tools but the probes can and will eventually give out.... but only when you need the thermometer the most... so be a wise shopper... have one if not two extra probes around as probes only go out when you need them the most. These probes are for the DTTC units that were manufactured during 2010 and beyond. If you need a DTTC probe replacement for units that were made prior to 2010 we can get them for you but just don't always keep too many on hand. Look for our packaged deals.. we do sell two of these at a time under our package deals!!! Wow!! But if you just want one.. then here you go!!