HDR Colour Picker?

I'm new to this unity thing and I keep seeing a HDR Colour Picker that has an intensity slider, can anyone tell me how to access it?

 

For c# script variables, use:

Code (csharp):

1. [ColorUsageAttribute(false, true)] public Color myColor;

or

Code (csharp):

1. [ColorUsageAttribute(false, true), SerializeField] private Color myColor;

The first bool is whether or not the color picker should show an alpha slider, the second is if the color is HDR or not.
https://docs.unity3d.com/ScriptReference/ColorUsageAttribute-ctor.html

For shader properties, use:

Code (csharp):

1. [HDR] _Color ("HDR Color", Color) = (1,1,1,1)