[fefrie]

It's like a double barreled shotgun shape and it holds the two cables so that when you slide it up and down, you can adjust the amount of 'split' between the left earbud cable and right earbud cable.
 
And any ideas where I could get them?

 

[PETEREK]

I'm not sure about the "double barrel" shape, but these will work. People call that part a 'chin-cinch', but they're just little o-rings.
 
Get the '8g' size in the drop down menu.
http://www.ebay.com/itm/V060-Replacement-Silicone-Clear-O-Rings-Bands-Seals-14G-to-1-1-4-2-5mm-to-32mm-/120806477345?var=&hash=item1c20a08e21mXIWuZIZYwkxp1X8367aZxg