Greisinger gkf 125 probe for compost grain and other similar media greisinger gkf 125 p the greisinger gkf 125 is a probe for compost grain and other similar media the probe has a rigid design and responds within seconds with the temperature the stainless steel v4a tube is 8mm in diameter and is fitted with a din type flat pin plug p greisinger gkf 125 temperature sensor