The Gary Fong AmberDome for Lightsphere Universal, Lightsphere Collapsible and Lightsphere II Cloud is great for warming the colour of light being output by your flash so you can better match it to the lighting in the environment you are shooting, particularly in daylight or indoors where there is ambient tungsten lighting.
What is so neat about the ability to "swap tops" is it is so fast to switch. Rather than switching the whole Lightsphere, or having to custom white balance your camera, if you want warm lighting, just put the top on and you're good to go!
Outdoors at dusk or early morning
Outdoors in Open Shade (set camera to auto-white balance)
Interiors with tungsten lighting (set camera WB to "tungsten" setting)
Shooting sunsets with the sun at your subject's back
Compatible with Lightsphere Universal, Lightsphere Collapsible and Lightsphere II Cloud