HOKE Gyrolok Calibration Fittings save time and money by reducing the time required to calibrate differential pressure transmitters. HOKE’s calibration fi ttings, constructed of 316 Stainless Steel, combine a straight thread and conical metal-to-metal sealing surface on one end with a 1/4? Gyrolok tube fi tting on the other. This design allows the technician to easily calibrate the transmitter – in place – without removing the pipe plug/bleed port tap assemblies. No TFE tape is required. Gyrolok’s exclusive Controlled Ferrule Drive increases value - extending cycle life.