An early rumor suggested that the Galaxy S5 Prime, a premium version of the Galaxy S5, could launch as early as June. Now, we see in some official documents from Samsung a phone codenamed SM-G906S. This leak suggested that this is indeed the Galaxy S5 Prime.
The documents are for the Find My Mobile service that Samsung offers and the SM-906S is mentioned as one of the variants of the S5 that is supported by this service.
As we approach the possible date of release, we will be more sure if this device is what we are expecting now, now we have to wait to see more rumors or even official teases from Samsung.