Fowler Hi Cal Height Gage Probe Accessory Set - Full This complete set of Probe Accessories for the Fowler / Sylvac Hi Cal Height Gage includes the following items... 3mm Ruby Ball Probe 1mm Tungsten Carbide Ball Probe 3mm Knife-edge Measuring Probe 3mm Cylindrical Measuring Probe 90° Probe Holder M2.5 90° Probe Holder 4mm Disk Shaped Anvils 7.7mm x M2.5 11.5mm x M2.5 80mm Extension M2.5 2mm Ball Point M2.5 Probe Holder & 3mm Ruby Ball Probe M2.5 Wooden Box