Rollei 121 BC flash.   You can tell there was some minor battery corrosion at one time but doesn't seem to impact operation.   You can hear the high pitch whine when you put in the batteries.   I don't have a compatible camera to test it on so I am selling for parts only. 

Unless otherwise specified, all items are used, vintage items in "as-is" condition.  Every effort has been made to describe the item in detail.  Photographs should be considered part of the description.  If you have any questions, or want more info, feel free to ask me.  I strive to have happy satisfied customers.