Dear Nikon users, I just got used SD-8 battery pack for some time. There is one thing that bothering me about this battery pack since it didn't come with the manual. There are two connectors, one connects to SB-26/SB27 as the power supply cord. But, I could not figure out the other connector. When I plug it into sync. cord outlet (of SB-27), it fits perfectly. So, is the other connector from SD-8 a sync cord? How does it work? Thanks for any information. Untung S.