Small metal Part not recognised

Dear All,

First of all Greetings !!

I me new here hope will get the solutions from all you experts around here.

Pl. find the above link & advice which is that part and where is it to be placed. In the above image I am referring the one which is above the Sim Card Tray ( The one with two Hole on both the ends)

While changing the battery for my iphone 4g I tore it down and now while fixing screwing it back I am not able to make it out that from where it have arrived ??

Thanks & Regards
To ALL

Have a look at the iFixit guides, they do repair steps and tear downs that should help you

iPhone Repair - iFixit