Greisinger gtf 300 nicr ni standard measuring probe type k greisinger gtf 300 gs the greisinger gtf 300 gs is a type k wire probe mini thermocouple wire sensor for gases liquids and extremely small surfaces the sensor is supplied with 1m teflon insulated twisted wires terminated with a mini thermocouple plug greisinger gtf 300 gs type k wire probe mini thermocouple plug 65 to 400 deg