Default What flashtool is used for us GPE devices?

I've heard there is a BLU icon and another that says download the flashtool from Sonys site.

But I can't find either.

I'm trying to unlock the bootloader. I have the key from Sony.

The flashtool I have found on Sony's site is called Emma. But I think it's wrong cause no where in EMMA can I put in the unlock bootloader key.