Shock Adapter

I bought some new brighter bulbs for my bike off ebay and of course they did not fit. I was told by the seller that I need a shock adapter to get the bulb to plug into my bike. I was wondering if anybody might be able to help me with this issue or explain how this works. Any information would be sweet. Thanks.

yeah actually im kinda curious of what a shock adapter is too. i hope its not that rubber thing that goes on the back of the headlight to hold the bulb in...

Ok so I re-read the email and it said "stock adapter' which I still dont know what that is. If somebody can help with this that would be sweet. I really want to put these lights in.