child of "this"

child of "this"

Hi all,

I'm having a little trouble with selectors here - your help would be great!

HTML:
<div class="pro">
<div class="msk">
</div>
</div>

<div class="pro">
<div class="msk">
</div>
</div>


Now, I would like to add a hover event for each of the 'pro' divs, which fades out and in that div's child .msk div.

How do I select the child .msk of the pro that is being hovered?

I have tried:
$(this + ' .msk')
$(this ' .msk')

$('.msk') selects both of the .msk divs.

I got it working with this: $('.msk',this)
But I don't understand why that works, so it wont do me any good in the future.

Thanks!