50Ghz Cascade Z probe 150um pitch. 2.4mm connector. Usually reserved in pair: serial number D2747 and D2748. You HAVE to contact Normand Gravel to install and remove them. They are accessible only by Normand. Make sure you take a picture of the probe tips when you finish using them. You can do it by moving the probe close one to the other (like you would do to do the calibration) and take a picture of the screen with your cell phone.