I have the expo white balance lens cap. It's badass. However, shooting in natural light outdoors it's a bit of a hassle- what with all the changing light. Outdoors if you change locations a bunch you have to keep resetting the white balance. Not always convenient when shooting small kids.

Indoor natural light is a breeze. Set it once and you're good to go. Also totally awesome that it's a cap as I immediately lost my original lens cap the moment I pulled it outta the box.