If you remove the black cover from the Westcott umbrella, it can be used closer to the subject as a shoot-trough diffuser. 
You get so much softer and more diffuse light on your subject! 
You can use the black cover to turn the Westcott umbrella into a bounce source. In this way you get a more powerful light bundle back!

Info

- Opens and closes quickly 
- Remove the black cover and it can be placed close to the subject  for a shoot-through diffuser. 
 - Use the black cover to make a bounce source.