Hey..was surfing though ebay looking for M04 parts and came across this:

http://cgi.ebay.com/3Racing-Tamiya-M...item5ad130a084

I know that this sounds kinda stupid, but what does this do exactly and is it worth while upgrade?
Also, anyone have a pic of where this actually mounts to? I'm just having a hard time getting a visual of where this would go.