Speaker for my helmet

Where can I buy a minature speaker that is safe to use within my helmet? I do not want to use an in-ear set of 'phones under any circumstances.

Someone mentioned a soft 'teabag' type speaker but I cannot locate anything suitable.

Thank you

I can highly recommend bassmonster in helmet speakers, I have had two sets and they work really well

I am using Starcom speakers and leads wired to my Zumo GPS. About £45 for the speakers and leads (c/w mini jackplugs to fit Zumo). Speakers are flat and about 1 1/2, and fit nicely into each of the ear recesses of a BMW System 5 helmet.

The Autocom website speaker / wiring fitting insturcitons for many types of helmet. I found these useful when 'professionally' installing the speaker wiring into the helmet.