The cone angle that restricts the region where the light is projected. No light is projected outside the cone. The limiting cone angle is the angle between the spot light axis (the axis between the LightPosition and PointsAt properties) and the spot light cone. This property is defined in degrees and must be between 0 to 90 degrees.

public System.float LimitingConeAngle {get; set;}

'Declaration
 
Public Property LimitingConeAngle As System.Single