A delay line of individually selectable delay elements can operate as an oscillator in an open loop mode to track process variation or drive a clock signal that varies with temperatures and voltages in the system. An input register is configured to receive a predetermined quantity of data elements. Specifically, the adaptor includes the key core and defines an outer end surface having a raised portion of an elliptical shape and a corresponding handle that has an end opening that conforms to the elliptical shape and when in place is secured to the adaptor.