The C1LinearGauge control includes a pointer which indicates the selected C1Gauge.Value of the control. The pointer consists of the C1Gauge.Pointer element:

The C1Gauge.Pointer element appears by default as a blue tapering element, but you can customize the appearance of the C1Gauge.Pointer element by setting several properties in the GaugePointer class, including the GaugePointer.Length, GaugePointer.Offset, GaugePointer.Shape, GaugePointer.PointerStyle, GaugePointer.Template, GaugePointer.Visible, and GaugePointer.Width properties.
In the image above, the  C1Gauge.Pointer element is customized.