ICOMPROM ICOM Non-Volatile RAM Module

one day,i kill my ram-unit. i am loocking 4 an icom ram unit(board).
i found the advertisement on the internet(piexx site).
it's 4 751. & plug it in, just-ok. rcvd freq. :usb 7khz-31.000.1khz
by the way, what for piexx's button battery?
pse tell me, about it...!!..
de ds5rli from taegu ct. s-korea