Waygate Technologies DA503 [0500502] Thickness Probe, Steel 0.2 to 12 inches (5 to 300mm). The Waygate Technologies DA 503 Probe,a Baker Hughes business product (formerly GE Inspection Technologies), has a frequency of 2 MHz, and a range of 5.0 to 300 mm in steel. This probe also requires the KBA-533 probe cable.