Waygate Technologies ALPHA-2 DFR [113-527-660] Standard Delay Line Probe, 15 MHz, 0.3 Inch Contact Diameter. Contact Probe Requires C-604 Cable. The Waygate Technologies Alpha-2 DFR Contact Probe, a Baker Hughes business product (formerly GE Instpection Technologies), is an Alpha series probe with a 0.25" contact diameter and a frequency of 15 MHz. This probe requires the C-604 probe cable.