A b-bender is a device that you add to your guitar,
so you can get those multiple Double bends.
Its designed to raise the pitch of the B string a whole,
step or a freted note on the B string a whole step.
If you check out the URL i added in my first reply you,
can find out more about it.
Also check out the Hipshot site or the parsons-white site.
I think the string bender site has samples you can play,
to hear what it dos.....................

Mark